CA2193120A1

CA2193120A1 - Low volatility luricating compositions

Info

Publication number: CA2193120A1
Application number: CA002193120A
Authority: CA
Inventors: David Robert Adams; Paul Brice
Original assignee: Individual
Current assignee: ExxonMobil Chemical Patents Inc
Priority date: 1994-06-16
Filing date: 1995-06-12
Publication date: 1995-12-21
Also published as: DE69520432T2; AU689914B2; EP0765372B1; EP0765372A1; DE69520432D1; WO1995034618A1; ES2155522T3; AU2881295A

Abstract

This invention relates to low volatility 5W20, 5W30, 10W40, 10W50, 15W40 or 15W50 multigrade oils for crankcase lubrication of gasoline and diesel engines, the oils comprising a) basestock having an average basestock neutral number of not less than 105 for a 5W multigrade, not less than 145 for a 10W
multigrade and not less than 200 for a 15W multigrade; b) a detergent inhibitor package including an ashless dispersant comprising an oil soluble polymeric hydrocarbon backbone having functional groups in which the hydrocarbon backbone is derived from an ethylene alpha-olefin (EAO) copolymer or alpha-olefin homo- or copolymer having an Mn of from 500 to 7000, and preferably having 30 % of terminal vinylidene unsaturation, and c) a viscosity modifier. These multigrade crankcase oils provide better volatility with reduced use or even without the need for expensive light neutral basestocks or non-conventional lubricant basestocks, while at the same time providing adequate control of sludge and varnish.

Description

W095/34C18 - 2~31~ P~.lll-... J~
~ I

Low wlatilitv lubricatinq cc ""-osilions This invention relates to low volatility lubricating ~u~l~uo~iLiu~
s particularly multigrade oils for crankcase lubrication of gasoline and diesel engines.

Lubricating oils used in gasoline and diesel ~,, dl ,k..dses comprise a natural andlor synthetic basestock containing one or more additives to impart o desired ., hdld~,L~:d ~Li~,s to the lubricant. Such additives typically include ashless dispersant, metal detergent, dl ILiokiddl IL and antiwear ~U~ UUI ,e, Ib, which may be combined in a package, SUIIIeL;IIIeS referred to as a detergent inhibitor (or Dl) package. The additives in such a package may include f~ ,liona';~,ed polymers but these have relatively short chains, typically having a number average molecular weight ~n of not not more than 7000.

Multigrade oils ususally also contain one or more viscosity modifiers (VM) which are longer chain polymers, which may be fw l~liul lalised to provide other properties when they are known as multifunctional VMs ~or MFVMs), but primarily act to improve the viscosity ~,1 Idl d~ ,Lics of the oil over the operating range. Thus the VM acts to increase viscosity at high temperature to provide more protection to the engine at high speeds, without unduly increasing viscosity at low temperatures which would otherwise make starting a cold engine difficult. High temperature pelrulllldllct: is usually measured in terms of the kinematic viscosity (kV) at 1 00~C (ASTM D445), while low temperature pel rul 1l Idl ,-,e is measured in terms of cold cranking simulator (CCS) viscosity (ASTM D5293, which is a revision of ASTM
D2602).

Viscosity grades are defined by the SAE CldsaificdLion system according to these two temperature measurements. SAE J300 defines the following grades:

woss~6ls 2 1 ~ 3 i 2 0 SAE VISCOSITY GRADES

SAE viscosityMaximum CCS kV 100~C mm2/s kV 100~C mm2/s grade Viscosity minimum maximum 10-3Pa.s @~ (~C~
5W 3500 ~-25) 3.8 10W 3500 (-20) 4.1 15W 3500 ~-15) 5.6 20W 4500 ~-10~ 5.6 25W 6000 ~-5) 9.3 - 5.6 ~g.3 - 9.3 ~12 5 - 12.5 ~16.3 - 16.3 ~21.9 Multigrade oils meet the requirements of both low temperature and 5 high temperature pelru",d"~,e, and are thus identified by reference to both relevant grades. For example, a 5W30 multigrade oil has viscosity ~J Idl d~ ri~ that satisfy both the 5W and the 30 viscosity grade reqwrements - i e. a maximum CCS viscosity of 3500.10-3 Pa.s at -25~C, a minimum kV100~C of g.3 mm2/s and a maximum kV100~C of ~12.5 mm2/s.
~U
For multigrade oils to meet these high temperature viscosity requirements, it is necessary to add significant amounts of VM which in turn results in increased low temperature viscosity. In order to meet the requirements for wide multigrades such as 5W20, 5W30, 1 0W40, 1 0W50, 1 5W40 and 1 5W50, it is usual to reduce the basestock viscosity by blending in less viscous oils - i.e. to lower the average neutral number of the total basestock. if conventional mineral basestocks are used it is usual to replace higher viscosity base~lu~,ks such as 600N basestock in part by basestock of 1 50N or iess to improve CCS pel r.""an~,d in wide multigrades. This results in 2c the formulated oil becoming more volatile which in turn increases oil consumption.

WO95134618 219 ~ ~ 2 ~ r~ 72 ~ 3 An alternative means of reducing the basestock viscosity and therefore improving CCS pe,ru""d"ce is to employ so-called non-conventional ~ Iubricants (or NCL). Examples of NCLs are synthetic b~ce~ h~ such as polydl~hdolt:ril, oligomers (PAO) and diesters and specially processed mineral bdsesLu.,h~ such as basestocks hydrocracked or hy.llu,su,,,t,rised to give greater paraffinic content and iower aromatic content. These NCLs result in a smaller increase in volatility but are very expensive and do not respond well to conventional a~ lLio~iddl ll systems.

The American Petroleum Institute (API) in their Publication 1509 dated January 1993 entitled "Engine Oil Licensing and Certification System"
(EOLCS) in Appendix E, 1.2 provided a clas~iricdLiull of base~Luch~ in a number of categories, which are widely used in the lubricant inductry.
Conventional mineral basestocks are in Groups 1 and 2; NCLs are 5 b~C~I. ,ck~ that do not fall within those two Groups.

A new class of ashless ~lia~e, ~dl IL:~ ~.UI llprisil)9 fLJI l~iliUnd~ 7d andlorderivatized olefin polymers based on polymers synthesized using IlltLcll.,,elle catalyst systems are described in US-A-5128056, 5151204, 20 5200103, 5225092, 5266223, 5334775; WO-A-94/19436, 94113709; and EP-A~40506, 513157, 513211. These dispersants are described as having superior viauulllt:LI h, properties as expressed in a ratio of CCS viscosity to kV100~C.

23 It has now been found that certain multigrade crankcase oils may be formulated with this new class of dispersant to provide better volatility with reduced use or even without the use of expensive light neutral bast,aLùchs or non-conventional lubricant b~e~l~ ..ks. In particular the invention enables multigrade oils to be prepared with volatility pcl ~ " " Idl ,ce meeting the 30 requirements for Noack volatility, as proposed in VW 500.00, the proposed ACEA ~l~e~ ir,,~ -s and the proposed ILSAC GF-2 ~,ueuiricdLiùll, while at the same time providing adequate controi of sludge and varnish. Noack viscosity is measured by d~te, ll lil ,i"g the evaporative loss in mass~/O of an oil after 1 hour at 250~C according to the procedure of CEC-L-40-T-87.

WO 95134618 2 1 9 3 i 2 ~1 r~

Accordingly in one aspect the invention provides a low volatility multigrade crankcase lubricating oil meeting SAE J30C viscosity grade 5vV20, 5W30, 1 OW40, 1 OW50, 1 5W40 or 1 5W50 cr,l ",u, i~i"rJ.
a) basestock having an average basestock neutral number of not less than 105 for a 5W multigrade, not less than 145 for a 10W multigrade and not 1ess than 200 for a 1 5W multigrade, b) a detergent inhibitor package of lubricating oil additives including an ashless dispersant co",pri:,i"g an oil soluble polymeric hy-llucc~lbul) backbone having functional groups in which the hy.l,uc,dlbun backbone is o derived from an ethylene alpha-olefln (E-A0) copolymer or alpha-olefin homo-or copolymer having an Mn of from 500 to 7000, and c) a viscosity modifier CO~ JrjSjII9 one or more polymeric additive having an Mn of greater than 2û,000.

The oil may reduce or avoid the use of lighter mineral base~luck~, and/or reduce or avoid the use of non-conventional lubricants, but in a preferred aspect the oil is substantially free of non~onventional lubricants as basestock.

Preferably the oil is a muitigrade meeting the 5W30, 10W40 or 15W50 viscosity grade of SAE J300.

The oil preferably has a Noar,k volatility of not more than 17%, and more preferably not more than 13~~ for 1 OW and 1 5W multigrades, when 2~ measured according to CEC-L~0-T-87. The oil preferably meets the requirements of current spe~,iriudLiun~ for sludge and varnish control, for example as specified in the API SH and VW 50û.00 cl ~e~iri~ ons.

The oil preferably contains at least 2.0 mass~J0 of the ashless dispersant, more preferably at least 2 25 mass~/0, these percentages being based on active ingredient of the ashless dispersant additive.

In another aspect the invention provides the use in a multigrade crankcase oil of an ashless di~uel~2llL co",,urisil,g an oil soluble polymeric hyd, UCdl i on backbone having functional groups in which the hydrocarbon backbone is derived from an ethylene alpha-olefin (EA0) copolymer or alpha-olefin homo- or copolymer having an Mo of from 500 to 7000, to reduce the volatility of the oil. In a further aspect the invention provides a method of ~095~34618 2 1 9 3 ~ 2 ~ P~,ll~. _.. ~.~
~ j reducing lubricating oil consumption in an engine, in which the engine is lubricated with a multigrade crankcase oil containing an ashless dispersant cu",,u, i~i"g an oil soluble polymeric hyd~uca~ bul ~ backbone having functionaigroups in which the hy.ll UL,dlbUI I backbone is derived from an ethylene 5 alpha-olefin (EAO) copolymer or alpha-olefin homo- or copolymer having ~3û% terminal vinylidene unsaturation and an ~In of from 500 to 7000.

DETAILED DESCRIPTION
A. BASESTOC~

The basestock used in the lubricating oil may be selected from any of the natural mineral oils of API Groups 1 and 2 (EOLCS, Appendix E, 1.2) used in crankcase lubricating oils for spark-ignited and cu~,l,u,us~iu,,-ignitedengines. The basestock is selected within the cu, ,~l, ci ula of the invention, d~:lJendil ,9 on the viscosity grade intended for the formulated oil. Mineral basu~lucks are typically available with a viscosity of from 2.5 to 12 mm2/s,more usually from 2.5 to g mm2/s at 1 00~C. Mixtures of conventional base~luck~ may be used if desired.

B. ASHLESS DISPERSANT
The ashless dispersant comprises an oil soluble polymeric hydlucd~uun backbone having functional groups that are capable of a~ucidlil ,9 with particles to be dispersed. Typically, the di~ue, ::.dl IL::.
comprise amine, alcohol, amide, or ester polar moieties attached to the 2j polymer backbone often via a bridging group. The ashless dispersant may be, for example, selected from oil soluble salts, esters, amino-esters, amides, imides, and oxazolines of long chain hydl UUdl LJOn substituted mono and di~,dl ùu~yl.c acids or their anhydrides; thiocarboxylate derivatives of long chain hydrocarbons; long chain aliphatic hy.ll U~,dl bUI15 having a polyamine 30 attached directly thereto; and Mannich UUI ll~ l Isdliul I products formed by condenail ~y a long chain substituted phenol with formaldehyde and polyalkylene polyamine.
The oil soluble po!ymeric hy-ll UUdl uOn backbone used in an ashless diauel: dl ll~> in the detergent inhibitor package is selected from ethylene 3s alpha-olefin (EAO) copo!ymers and a!pha-olefin homo- and copolymers such as may be prepared using the new metallocene catalyst chemistry, which may wo 95134618 ~ 2 1 9 3 i ~

have a high degree, >30~~0, of terminal vinylidene unsaturation. The term alpha-olefin is used herein to refer to an olefin of the formula:
R' H--C =CH 2 wherein R' is preferably a C1 - C1 8 alkyl group. The requirement for 5 terrninal vinylidene unsaturation refers to the presence in the polymer of the following structure:
IR
Poly--C =CH 2 wherein Poly is the polymer chain and R is typically a C1 - C18 alkyl group, typically methyl or ethyl. Preferably the polymers will have at least o 50C~6, and most preferably at least 6Q~/c, of the polymer chains with terminalvinylidene unsaturation. As indicated in WO-A-94115426, ethylene/1-butene copolymers typically have vinyl groups terminating no more than about 10 percent of the chains, and internal mono-unsaturation in the balance of the chains. The nature of the unsaturation may be duLer",i"ed by FTIR
~,eul,.,scupic analysis, titration or C-13 NMR.
The oil soluble polymeric hydrocarbon backbone may be a homopolymer (e.g., polypropylene) or a copolymer of two or more of such olefins le.g., copolymers of ethylene and an alpha-olefin such as propylene or butylene, or copolymers of two different alpha-olefins). Other copolymers 20 include those in which a minor molar amount of the copolymer monomers, e.g., 1 to 10 mole ~,6, is an c~ diene, such as a C3 to C22 non-conjugated diolefin (e.g., a copo!ymer of isobutylsne and butadiene, or a copolymer of ethyiene, propylene and 1 ,4-hexadiene or 5-ethylidene-2e-~u, LJUI "ene).
Atactic propylene oligomer typically having h/ln of from 700 to 5000 may also 25 be used, as described in EP-A-490454, as well as heteropolymers such as polyepoxides One preferred class of olefin polymers is polybutenes and b,uc~ iu~A.'y poiy-n-butenes, such as may be prepared by poly",~ dliUn of a C4 refinery stream. Other preferred classes of olefin polymers are EAO copolymers that 3u preferably contain 1 to 50 mole~~O ethylene, and more preferably 5 to 48 mole~/O ethylene. Such polymers may contain more than one alpha-olefin and WO 9~5/34618 2 ~ 9 3 1 ~ 1 !L
~ 7 may contain one or more C3 to C22 diolefins. Also usable are mixtures of EAO's of varying ethylene content. Different polymer types, e.g., EAO, may ~ alsobemixedorblended,aswellaspolymersdifferinginMn;cu,,,pùne,,t~
derived from these also may be mixed or blended.
s The olefin polymers and copolymers preferably have an Mn of from 700 to 5000, more preferably 2000 to 5000. Polymer molecular weight, s,u~,uiriudlly Mn~ can be determined by various known techniques. One convenient method is gel pel",edlion u hl UllldLU-JI duhy (GPC), which acldiliu~ ,ally provides molecular weight distribution i"~u, IlldLiul, (see W. W.
Yau, J. J. Kirkland and D. D. Bly, "Modern Size Exclusion Liquid Chlulllalu~u,ld,uhy",JohnWileyandSons,NewYork,1979). Anotheruseful method, particularly for lower molecular weight polymers, is vapor pressure osmometry (see, e.g., ASTM D3592).
The degree of polymerisation Dp of a polymer is:

D ~ Mn x mol.~~O monomer i 100 x mol.wt monomer i and thus for the copolymers of two monomers Dp may be caiculated as follows:
Mn x mol.~~O monomer 1 + Mn x mol.~/O monomer 2 Dp 100 x mol.w~ monomer 1 100 x mol.wt monomer 2 In a preferred aspect of the invention the degree of pol~""e, i~dliul ~ for the polymer bachbu"es used in the invention is at least 45, typically from 50 to 165, more preferably 55 to 140.
Particularly preferred copolymers are ethylene butene copolymers.
In a preferred aspect of the invention the olefin polymers and 2~J copolymers may be prepared by various catalytic pol~",lt:, i~dLion processes using Ill~:tdlloctl ,~ catalysts which are, for example, bulky ligand transitionmetal compounds of the forrnula:

[L]mM[A]n WO 9~ K18 i 219 3 i 2 a . ~"~. A

where L is a bulky ligand; A is a leaving group, M is a transition metal, and m and n are such that tile total ligand valency co" ~a~Ond:~ to the transition metal valency. Preferably the catalyst is four co-ordinate such that the compound is ionizaole to a 1 + valency state.
The ligands L and A may be bridged to each other, and if two iigands A and/or L are present, they may be bridged. The metallocene compound may be a full sandwich compound having two or more ligands L which may be cyi,lope~ ,ladie, lyl ligands or cy~lope"Lddie, Iyl derived ligands, or they may be half sandwich compounds having one such ligand L. The ligand may be mono- or polynuclear or any other ligand capable of r~-5 bonding to the transition metal.
One or more of the ligands may ~I-bond to the transition metal atom, which may be a Group 4, 5 or 6 transition metal and/or a lanthanide or actinide transition metal, with zirconium~ titanium and hafnium being particularly preferred.
The ligands may be c~ ~hstih ~tPd or unsl ~hstitl ~t~l, and mono-, di-, tri, tetra- and penta-substitution of the cyclopentadienyl ring is possible.
Optionally tne substituent(s) may act as one or more bridges between the ligands and/or leaving groups andlor transition metal. Such bridges typically comprise one or more of a carbon, germanium, silicon, phosphorus or nitrogen atom-containing radical, and preferabiy the bridge places a one atom link between the entities being bridged, although that atom may and often does can-y other substituents.
The ~I~eldll-~cene may also contain a further dicrlR~eRhle ligand, preferably displaced by a cocatalyst - a leaving group - that is usually selected from a wide variety of hydrocarbyl groups and halogens.
Such pol~",~ dLi~ 5, catalysts, and cocatalysts or activators are described, for example, in US-A-4530914, 4665208, 4808561, 4871705, 4897455, 4937299, 4952716, 5017714, 5055438l 5û57475, 5064802, 5096867, 5120867, 5124418, 5153157, 5198401, 5227440, 5241025; EP-A-129368, 277003, 277004, 420436, 520732; and WO-A-91/04257, 92/00333 93/08199, 93108221, 94/07928 and 94/13715.
The oil soluble polymeric hydrocarbon backbone may be ful ~ iondli~e~l to incorporate a functionai group into the backbone of the WO 9S/34618 2 1 3 3 ~ /~ L

polymer, or as one or more groups pendant from the polymer backbone. The functional group typically will be polar and contain one or more hetero atoms such as P, O, S, N, halogen, or boron It can be attached to a saturated hyd, Ul,dl LJUI I part of the oil soluble polymeric hydl UGdl iJUI I backbone via 5~ Ihstitution reactions or to an olefinic portion via addition or cyclod i iiliu"
reactions. Alternatively, the functional group can be illuù~,uùlclled into the polymer in conjunction with oxidation or cleavage of the polymer chain end (e.g., as in ozonolysis).
Useful fu,,._Liù,)ali~dLiu,, reactions include: hdlûgendLiull of the polymer o at an olefinic bond and subsequent reaction of the halogenated polymer with an ethylenically unsaturated functional compound ~e.g., maleation where the polymer is reacted with maleic acid or anhydride); reaction of the polymer with an unsaturated functional compound by the "ene" reaction absent hdlogendliûn, reaction of the polymer with at least one phenol group (this permits derivatization in a Mannich base-type cul1densdLiu"); reaction of the polymer at a point of unsaturation with carbon monoxide using a Koch-type reaction to introduce a carbonyl group in an iso or neo position; reaction of the polymer with the funuLiu, ,alizil ,9 compound by free radical addition usinga free radical catalyst; reaction with a thiocarboxylic acid derivative; and 20 reaction of the polymer by air oxidation methods, ~po~ iol l, ul llo, Udl I lil IdLiOIl, or ozonolysis.
The functionalized oil soluble polymeric hydl UCdl bul ~ backbone is then further derivatized with a nucleophilic reactant such as an amine, amino-alcohol, alcohol, metal compound or mixture thereof to form a cuu usuuudiug derivative. Useful amine compounds for derivatizing fu, IuLiuuali~ed polymers comprise at least one amine and can comprise one or more additional amine or other reactive or polar groups. These amines may be hydrocarbyl amines or may be p, ~:domil Idl ILIy hydrocarbyl amines in which the hydrocarbyl group includes other groups, e.g., hydroxy groups, alkoxy groups, amide groups, 30 nitriles, illlidd~ul;l ,e groups, and the like. Particularly useful amine compounds include mono- and polyamines, e.g. polyalkylene and polyoxyalkylene polyamines of about 2 to 60, conveniently 2 to 40 (e.g., 3 to 20), total carbon atoms and about 1 to 12, conveniently 3 to 12, and preferably 3 to 9 nitrogen atoms in the molecule. Mixtures of amine 3~ compounds may advantageously be used such as those prepared by reaction of alkylene dihalide with ammonia. Preferred amines are aliphatic saturated WO95/.34618 2193~ 20 IIrl ~

amines, including, e.g., 1,2-d;d",i"o~ll,ane; 1,3-did~ ou~upa~le; 1,4-diaminobutane; 1 ,6~1idl~ ul ,exd"e; polyethylene amines such as diethylene triamine; triethylene tetramine; tetraethylene pe, lldl "i"e, and polypropyle,led",i"cs such as 1,2-propylene diamine; and di-(1,2-5 propylenejtriamine.
Other useful amine compounds include: alicyclic diamines such as1,4-di(cllli"o"lt:ll,yl~ cyclolle~d"a, and heterocyclic nitrogen compounds such as illlidd~ulil ,es. A particularly useful class of amines are the polyamido andrelated amido-amines as disclosed in US 4,857,217; 4,956,107; 4,g63,275;
o and 5,22g,022. Aiso usable is tris(hydroxymethyl)amino methane (THAM) as described in US 4,102,798; 4,113,639; 4 116,876; and UK 989,409.
Dendrimers, star-like amines, and comb-structure amines may also be used.
Similarly, one may use the culldtlls~d amines disclosed in US 5,053,152 The ful luliondli~d polymer is reacted with the amine compound according to 5 conventional techniques as described in EP-A 208,560, US 4,234,435 and US 5,229,022 .
The ful l~liul ,ali~d oif soluble poiymeric hy~ll UUdl L)CII ~ backbones also may be derivati~ed with hydroxy compounds such as monohydric and polyhydric alcohols or with aromatic compounds such as phenols and 20 naphthols. Polyhydric alcohols are preferred, e.g., alkylene glycols in which the alky!ene radical contains from 2 to 8 carbon atoms. Other useful polyhydric alcohols include glycerol, mono-oleate of glycerol, monostearate of glycerol, ll~onu~"~lhyl ether of glycerol, pentaerythritol, dipentaerythritol, and mixtures thereof. An ester dispersant may also be derived from 25 unsaturated alcohols such as allyl alcohol, cinnamyl alcohol, propargyl alcohol, 1-cyclohexane-3-ol, and oleyl alcohol. Still other classes of the alcohols capable of yielding ashless di~ue, ~dl 1~ comprise the ether-alcohols and including, for example, the oxy-alkylene, oxy-arylene. They are exemplified by ether-alcohols having up to 150 oxy-alkylene radicais in which 30 the alkylene radical contains from 1 to 8 carbon atoms. The ester di::.pt~ dl ll~i may be di-esters of succinic acids or acidic esters, i.e., partially esterified succinic acids; as well as partially esterified polyhydric alcohols or phenols, i.e., esters having free alcohols or phenolic hydroxyl radicals. An ester di~,ue, ::~dl 11 may be prepared by one of several known methods as 35 illustrated, for example, in US 3,381,022.

~1 n ~ 3 t3 WO 95/34618 f.~ l J ~ 1 61 lJ A ~ 111!~1, _. /~
~ Il A preferred group of ashless dispersants includes those s~ ~hst~ d with succinic anhydride groups and reacted with polyethylene amines (e.g., tetraethylene pentamine~, dl"i"oal~uhols such as trismethylolc,,,i,,u,,,clhc,,e and optionally additional reactants such as alcohols and reactive metals e.g., ~ 5 pentaerythritol, and collluilldliol)s thereof). Also useful are di~uc~d~
wherein a polyamine is attached directly to the backbone by the methods shown in US 3,275,554 and 3,565,804 where a halogen group on a halogc, ,dted hydl uw, L,on is displaced with various alkylene polyamines.
Another class of ashless dia,ue, ~a"b comprises Mannich base o cot)dcnsdlio" products. Generally, these are prepared by con.lcna;l l9 aboutone mole of an alkyl-sl Ih5tjh IlPd mono- or polyhydroxy benzene with about 1 to 2.5 moles of carbonyl compounds (e.g., formaldehyde and pdl crul l,laldel ,yde) and about 0.5 to 2 moles polyalkylene polyamine as disclosed, for example, in US 3,442,808. Such Mannich cundel)satiu"
products may include a polymer product of a l "cLdlloce~le cataylsed pol~,,lcri~dlion as a substituent on the benzene group or may be reacted with a compound containing such a polymer substituted on a succinic anhydride, in a ",d""e,~i",ilc, to that shown in US 3,442,8û8.
Examples of fu"uliundli~ed and/or derivatized olefin polymers based on polymers synthesized using ~ ~ le~allu~cne catalyst systems are described in publications identified above.
The dispersant can be further post-treated by a variety of conventional post tl,:dLIll~ , such as boration, as generally taught in US 3,087,936 and 3,254,025. This is readily a~culll,ul,~lleo by treating an acyl nitrogen-containing di::~,Udl aal 11 with a boron compound selected from the group consisting of boron oxide, boron halides, boron acids and esters of boron acids, in an amount to provide from about û.1 atomic proportion of boron for each mole of the acylated nitrogen composition to about 2û atomic ,UI UUUI Ik~na of boron for each atomic proportion of nitrogen of the acylated nitrogen r,u,,,,uosilioll~ Usefully the dispe~d~lL~ contain from about 0.05 to 2.û
wt. %, e.g. 0.05 to 0 7 wt. ~/0 boron based on the total weight of the borated ~ acyl nitrogen compound. The boron, which appears be in the product as dehydrated boric acid polymers (pnmarily ~HB02)3), is believed to attach to the dispersznt imides and diimides as amine salts e.g., the ~,,ciabo~dlc salt of3S the diimide. Boration is readiiy carried out by adding from about 0.05 to 4, e.g.,1 to 3 wt. ~~ (based on the weight of acyl nitrogen compound) of a boron WO ~34618 ~ 1 a ~ 1 ~ U [~

compound, preferably boric acid, usually as a slurry, to the acyl nitrogen compound and heating with stirring at from 135~ to 190~ C, e.g., 140~-170~ C, for from 1 to 5 hours followed by nitrogen stripping. Alternatively, the boron treatment can be carried out by adding boric acid to a hot reaction mixture of the dicarboxylic acid material and amine while removing water.

C. VISCOSITY MO~iFIERS
The viscosity modifier used in the invention functions to impart high and low temperature operability to a lubricating oil The VM used may have 10 that sole function, or may be multifunctional.

Multifunctional viscosity modifiers that aiso function as di~ d~ are also known and may be prepared as described above for ashless dispersants. The oil soluble polymeric hydl t,)Cdl bUI 1 backbone wili usually have a M~ of from 20 000, more typically from 20,000 up to 500,000 or greater. In general, these dispersant viscosity modifiers are functionalized polymers (e.g. inter polymers of ethylene-propylene post grafted with an active monomer such as maleic anhydride) which are then derivatized with, for example, an alcohol or amine.
Suitable compounds for use as monofunctional viscosity modifiers are generally high molecular weight hy.l, U-,dl bu~ I polymers, including polyesters.
Oil soluble viscosity modifying polymers generally have weight average molecular weights of from about 1 0,û00 to 1 ,000~0ûû, preFerabiy 20,000 to 25 500,000, which may be d~ ll"i"ed by gel pelll,ecliu~l chromatography (as described above) or by light scattering.

Re,c,use"ldtive examples of suitable viscosity modifiers are polyisobutylene, copolymers of ethylene and propylene and higher alpha-30 olefins, poly",uil ,aw ylates, polyalkylmethacrylates, methacrylate copolymers,copolymers of an unsaturated dicarboxylic acid and a vinyl compound, inter polymers of styrene and acrylic esters, and partially hydlugendtud copolymers of styrenel isoprene styrene/butadiene, and isoprene/butadinne, as well as the partially hydrogenated homopolymers of butadiene and 3s isoprene and isopreneldivinylbenzene.

WO 95/34618 2 1 9 3 ~ ~ O A ~
~ 13 The viscosity modifier can be chosen from any of the above categories oF additive in such an amount to obtain the multigrade viscosity requirements of the oil of the invention. It is preferably a polyisobutylene or copolymer of ethylene and propylene or higher alpha-olefin, as such viscosity modifiers are 5 particulzrly economic and effective. However to obtain oiis having a particularly high shear stability a highly shear stable viscosity modifier having an SSI of 5 or less may be used and such viscosity modifiers include in particular hydl ugundLed polyisoprene star polymers and hydl ugtl1dlud styrene-isoprene block copolymers. An example of cu,l""u,.,ially available o viscosity modifers of this type is the family of products sold by Shell Il ,lu" Idliul ,al Chemical Co. Limited as their ShellvisT~ 200 series.

The viscosity modifier used in any aspect of the invention wili be used in an amount to give the required viscosity chdl ~ulel i~Lics. Since they are 15 typically used in the form of oil solutions the amount of additive employed will depend on the co"~,e"L, dlion of polymer in the oil solution ,,u",ul i~i"g the additive. However by way of illustration, typical oli solutions of polymer used as VMs are used in amount of from 1 to 30~/0 of the blended oil. The amount of VM as active ingredient of the oil is generally from 0.01 to 6 wt%, and more 20 preferably from 0.1 to 2 wt%.

OTHER DETERGENT INHIBITOR PACKAGE ADDITIVES

Additional additives are typically ill~;u~o~clud into the co,,,uo~iLiuu~ of 25 the present invention. Examples of such additives are metal or ash-containing dule, u~u, ILa, dl ILiU~iddl 11~, anti-wear agents, friction modifiers, nust inhibitors, anti-foaming agents, demulsifiers~ and pour point .lel,, u:,sa, lla.
Metal-containing or ash-forming d~ yur~la function both as 30 dele,ye"l~ to reduce or remove deposits and as acid neutralizers or rust inhibitors, thereby reducing wear and corrosion and extending engine life.
Detergents generally comprise a polar head with a long hydrophobic tail, with the polar head cu"l,urisil,g a metal salt of an acidic organic compound. The salts may contain a sub~ld"li.,"y ~lui!_l ,io",ell ic amount of the metal in which 35 case they are usually described as normal or neutral salts, and would typically have a total base number or TBN (as may be measured by ASTM
D2896) of from 0 to 80. It is possible to include large amounts of a metal base by reacting an excess of a metal compound such as an oxide or hydroxide WO95134618 ~ ~3 1 with an acidic gas such as carbon dioxide. The resulting overbased detergent comprises neutralised detergent as the outer layer of a metal base (e.g.
carbonate) micelle. Such overbased ~ L~, yel ,L~ may have a TBN of 150 or greater, and typically of from 250 to 450 or more.
Detergents that may be used inciude oil-soluble neutral and overbased sulfonates, phenates~ sulfurized phenates, Lhioulloa~holldlus, salicylates, and I la,uh t he:l lal~5 and other oil-soluble carboxylates of a metal, particularly the alkali or alkaline earth metals, e.g., sodium, potassium, lithium, calcium, and o magnesium. The most commonly used metals are calcium and magnesium, which may both be present in d~ yel ,I:, used in a lubricant, and mixtures of calcium and/or magnesium with sodium. Particularly convenient metal d~lelyt~ are neutral and overbased calcium sulfonates having TBN of from 20 to 450 TBN, and neutral and overbased calcium phenates and sulfurized phenates having TBN of from 50 to 450.

Sulfonates may be prepared from sulfonic acids which are typically obtained by the sulfonation of alkyl s~ IhCtitl rt~d aromatic hyll UUdl bSII)S such as those obtained from the r, d~,Liul IdLiUIl of petroleum or by the alkylation of 20 aromatic hydl uw, bùn~. Examples included those obtained by alkylating benzene~ toluene, xylene, nd~hLI ,al~"e, diphenyl or their halogen derivatives such as ~hlo, uL,e"~, le, chlorotoluene and ~hlo, u, IdUi 11l ,alcne. The alkylation may be canried out in the presence of a catalyst with alkylating agents having from about 3 to more than 70 carbon atoms. The alkaryl 2~ sulfonates usually contain from about 9 to about 80 or more carbon atoms, preferably from about 16 to about 60 carbon atoms per alkyl sl Ihstitl ItPd aromatic moiety.

The oil soluble sulfonates or alkaryl sulfonic acids may be neutralized 30 with oxides, hydroxides, alkoxides, carbonates, carboxylate, sulfides, hydrosulfides, nitrates, borates and ethers of the metal. The amount of metal compound is chosen having regard to the desired TBN of the final product but typically ranges from about 100 to 220 ~vt C/o ~preferably at least 125 wt ~/0) of that sLoi"l,iG",~I,iually required.
3'i l~etal salts of phenols and sulfurised phenols are prepared by reaction with an dlJ,UI u,uriale metal compound such as an oxide or hydroxide and neutral or overbased products may be obtained by methods well known in the wo 95/34618 2 1 ~ 3 1 2 ~1 1 ~IILI _. . .'.S
~ 15 art. Sulfurised phenols may be prepared by reacting a phenol with sulfur or a sufur containing compound such as hydrogen sulfide, sulfumllollol ' 'e or sulfur dihalide, to form products which are generally mixtures of compounds in which 2 or more phenols are bridged by sulfur containing bridges.

Dihydrocarbyl diLhiuiJho~,l ,dle metal salts are frequently used as anti-wear and dl ILiG~iddl IL agents. The metal may be an alkali or alkaline earth metal, or aluminum, lead, tin, molybdenum, Illdl Iydl ~e5e, nickel or copper.
The zinc salts are most commonly used in lubricating oil in amounts of 0.1 to o 10, preferably 0.2 to 2 wt. ~/0, based upon the total weight of the lubricating oil cu~ o~ilio, ,. They may be prepared in accol ddl ,ce with known techniques by first forming a dihydrocarbyl dithiv~hus~llol ic acid (DDPA), usually by reaction of one or more alcohol or a phenol with P2Ss and then neutralizing the formed DDPA with a zinc compound. For example, a .liLhio,ohu~.l ,u, i~, acid may be made by reacting mixtures of primary and secondary alcohols.
Alternatively, multiple iiLI ,io,~hua~ ol ic acids can be prepared where the hydrocarbyl groups on one are entirely secondary in character and the hydrocarbyl groups on the others are entirely primary in character. To make the zinc salt any basic or neutral zinc compound could be used but the 20 oxides, hydroxides and wlbolldLes are most generally employed.
Commercial additives frequently contain an excess of zinc due to use of an excess of the basic zinc compound in the neutralization reaction.

The preferred zinc dihydrocarbyl dithiophosphates are oil soluble salts 25 of dihydrocarbyl diLl ,iupllua,ul ,f fic acids and may be l ~ s~l lLed by the following formula:
RO~
P--S Zr~
R' .2 wherein R and R' may be the same or different hydrocarbyl radicals containing from 1 to 18, preferably 2 to 12, carbon atoms and including 30 radicals such as alkyl, alkenyl, aryl, arylalkyl, alkaryl and cy.' 'i, hdli~.radicals. Particularly preferred as R and R' groups are alkyl groups of 2 to 8 carbon atoms. Thus, the radicals may, for example, be ethyl, n-propyl, i-propyl, n-butyl, i-butyl1 sec-butyl, amyl, n-hexyl, i-hexyl, n-octyl, decyl, dodecyl, octadecyl, 2-ethylhexyl, phenyl, butylphenyl, cyclohexyl, 35 methylcyclopentyl, propenyl, butenyl. In order to obtain oil solubility, the total _ _ _ _ _ , . _ _ _ _ _ _ ... . . . . . . . . ... ... .. . ... . . ...

Wl~9~V34618 2l93~a l~
IG

number of carbon atoms (i e. R and R'~ in the diLhiuphoaullùrk, acid will generally be about 5 or greater. The zinc dihydrocarbyl .lill ,iophr sul Idt'3 can therefore comprise zinc dialkyl diL hiuuhOSuhali 5. Conveniently at least 50 (mole) ~/O of the alcohols used to introduce hydrocarbyl groups into the s dilhio~.ho:".l IUI il.. acids are secondary alcohols.

Oxidation inhibitors or dl ILiUiU(.Idl IL~ reduce the tendency of mineral oils to .luteriu, dt'3 in service which cluleriordLio~l can be evidenced by the products of oxidation such as sludge and varnish-like deposits on the metal surfaces o and by viscosity grovith. Such oxidation inhibitors include hindered phenols, alkaline earth metal salts of alkylpher,ulLl,ioe~le,:, having preferably Cs to C12 alkyl side chains, calcium nonylphenol sulfide, ashless oil soluble phenates and sulfurized phenates, phosphosulfurized or sulfurized hyulucdliJulls~ phu~u;lolulJs esters, metal Lllio~dlbdllldLes, oil soluble copper 15 compounds as described in US 4,867,890, and molybdenum containing compounds.

Typical oil soluble aromatic amines having at least two aromatic groups attached directly to one amine nitrogen contain from 6 to 16 carbon 20 atoms. The amines may contain more than two aromatic groups.
Compounds having a total of at least three arorr,atic groups in which two aromatic groups are linked by a covalent bond or by an atom or group (e.g., an oxygen or sulfur atom, or a -CO-. -SO2- or alkylene group) and two are directly attached to one amine nitrogen also considered aromatic amines.
25 The aromatic rings are typically substituted by one or more substituents selected from alkyl, cycloalkyl, alkoxy, aryloxy, acyl, acylamino, hydroxy, and nitro groups.

Friction modifiers may be included to improve fuel economy. Oil-30 soluble alkoxylated mono- and diamines are well known to improve boundary layer lubrication. The amines may be used as such or in the form of an adduct or reaction product with a boron compound such as a boric oxide, boron halide, ~ Ldi o, alu, boric acid or a mono-, di- or trialkyi borate.

Other friction modifiers are known, Among these are esters formed by reacting carboxylic acids and anhydrides with alkanols. Other conventional friction modifiers generally consist of a polar terminal group ~e.g. carboxyl orhydroxyl) covalently bonded to an oleophillic hydrocarbon chain. Esters of 21~312i1 W0 95/34618 ~ ' IL
~ 17 carboxylic acids and anhydrides with alkanols are described in US 4,702,850.
Examples of other conventional friction modifiers are described by M. Belzer in the "Journal of Tribology" (1992), Vol. 114, pp. 675-682 and M. Belzer and S. Jahanmir in "Lubrication Science" (1988), Vol. 1, pp. 3-26.

Rust inhibitors selected from the group consisting of nonionic polyoxyalkylene polyols and esters thereof, polyoxyalkylene phenols, and anionic alkyl sulfonic acids may be used.

o Copper and lead bearing corrosion inhibitors may be used, but are typically not required with the formulation of the present invention. Typically such compounds are the thiadiazole polysulfides containing from 5 to 50 carbon atoms, their derivatives and polymers thereof. Derivatives of 1,3,4 Il,;~,l;-,,nl~s such as those described in U.S. Pat. Nos. 2,719,125; 2,719,126;
and 3,087,932; are typical. Other similar materials are described in U.S Pat.
Nos. 3,821,236; 3,904,537; 4,097,387; 4,107,059; 4,136,043; 4,188,299; and 4,193,882. Other additives are the thio and polythio sulr~na",idus of I h;a~ s such as those described in UK. Patent Specification No.
1,560,830. Btl ,~ul, id ~ules derivatives also fall within this class of additives.
When these compounds are included in the lubricating uolll,uo~iLiun, they are preferrably present in an amount not exceding 0.2 wt ~/O active ingredient.

A small amount of a demulsifying component may be used. A
preferred demulsifying component is described in EP 330,522. It is obtained 2i by reacting an alkylene oxide with an adduct obtained by reacting a bis-epoxide with a polyhydric alcohol. The demulsifier should be used at a level not exceeding 0.1 mass ~/O active ingredient. A treat rate of 0.001 to 0.05 mass ~/0 active ingredient is convenient.

Pour point ;I~IU~ ~SSdl IIS, otherwise known as lube oil flow improvers, lower the minimum temperature at which the fluid will flow or can be poured.
Such additives are well known. Typical of those additives which improve the low temperature fluidity of the fluid are Cg to C 13 dialkyl fumarate/vinyl acetate copolymers and polyalkylmethacrylates.

Foam control can be provided by many compounds including an dl llirUdll Idl ll of the polysiloxane type, for example, silicone oil or polydimethyl siloxane.

WO 95~34618 2 1 ~ 3 i 2 ~
~x Some of the above-mentioned additives can provide a multiplicity of effects; thus for example, a single additive may act as a dia,u ~ a~ oxidation inhibitor. This approach is well known and does not require further 5 t:ldLIUl dLiUI 1.

When lubricating ~,ull~po~ s contain one or more of the above-mentioned additives, each additive is typically blended into the base oil in an amount which enables the additive to provide its desired function.
o R~ se"ldlive effective amounts of such additives, when used in crankcase lubricants, are listed below. All the values listed are stated as mass percent active ingredient.

ACDITIVE MASS ~/O MASS ~/C
(Broad) (Preferred) Ashless Dispersant 0.1 - 20 1 - 8 Metal d~le, l2~e, ILa 0 1 - 15 û.2 - 9 Corrosion Inhibitor 0 - 5 0 -1 5 Metal dihydrocarbyl dilhiuul lO:~lJhdle 0 1 - 6 0.1 - 4 Su,.~lell,ellLdl anti-oxidant 0 -5 0.01 - 1.5 Pour Point Depressant 0.01 - 5 0.01-1.5 Anti-Foaming Agent û - 5 0.001-0.15 SU~ ILdl Anti-wear Agents 0 - 0.5 0 - û.2 Friction Modifier 0 - 5 0 -1.5 Viscosity Modifier 0.01- 6 0 - 4 Mineral Base Oil Balance Balance .

The uu" ,~on~ ,t~ may be incorporated into a base oil in any convenient way. Thus, each of the co" ~Junel IL~ can be added directly to the oil by dispersing or dissolving it in the oil at the desired level of cu"ue, ILI ~Liun.Such blending may occur at ambient temperature or at an elevated temperature.

Preferably all the additives except for the viscosity modifier and the pour point deu, ~SScll ,[ are blended into a cu, ,cc, I[l dlu or additive package described herein as the detergent inhibitor package, that is subsequently blended into basestock to make finished lubricant. Use of such ~,u, ,w"I, dL~s 1t~3 WO 95/34618 2 ~ 1 r~
~ 1., is conventional. The conce"L,dL~ will typically be formulated to contain the additivels) in proper amounts to provide the desired cu, ICt~ dLiol, in the final formulation when the conce, ILI dit:H S combined with a ~,, udeIt:, I l lil ,ed amount of base lubricant.
~ 5 Preferably the concel ,I, dLe is made in a~L,ul ddl ,I e with the method described in US 4,938,880. That patent describes making a premix of ashless dia,ueradl ,I and metal .leL~I ye"L~ that is pre-blended at a temperature of at least about 1 00~C. Thereafter the pre-mix is cooled to at least 85~C and o the additional cwllyonellLa are added The final formulations may employ from 2 to 15 mass 0/D and preferably 5 to 10 mass ~h, typically about 7 to 8 mass ~h of the concel ,I, dLI:: or additive package with the remainder being base oil.

The invention will now be described by of illustration only with reference to the following examples. In the examples, unless otherwise noted, all treat rates of all additives are reported as mass percent active ingredient.

Examples ComParative ExamPles 1 and 2~ and ExamPles 1 and 2 A series of multigrade crankcase lubricating oils meeting API SH/CD
Cpel ;r;,~ l Is were prepared from a mixture of a non-conventional lubricant, a hydlu~,lduhed basestock cull""e",_idlly available as Shell XHVI5.7 (~Ill~uli:.illg 20 mass~/O of the oil), and one or more mineral tdae~Lu.,hs, a detergent inhibitor package ~Dl package) containing an ashless dispersant, 30 ZDDP, cllIi.w~iddill, metal-containing dttely~"Ls, friction modifier, demulsifier, and an antifoam agent, and a separate viscosity modifier and pour point d~ asd, IL.

The Comparative Examples used a conventional borated 35 polyisobutenyl succinimide dispersant (PIBSAIPAM), whereas Examples of the invention used an ashless .li~pel ~a"Ls having an ethylenelbutene copolymer backbone (M~ by GPC = 2400, ethylene content = 39 mole~h, terminal vinylidene = 64%) functionalised by the introduction of a carbonyl WO95/346t% 2193 1~ r~ r j~
2~) ~

group by the Koch reaction which is in turn reacted with a polyamine and borated (EBCO/PAM). The ~ .ldl dliOI I of such an ashless cli~ l ad"l is described in WG-A-9411 370g. The EBCOIPAM ashless .lispe, ::ldl lla was used at a lower treat rate ~2.4 mass~/0) to that used for PIBSAIPAM, since the better dispersant p~, ru""d,lce of the former means that a smaller quantity is required to achieve adequate performance. The kV100~C and CCS viscosity at -20~C for each oil was measured, and the average basestock neutral number (ave. BSNN~ de~e""i"ed from the fonmula:
log (ave. BSNN) = BSR1 x log (BSNN1)/100 ~ BSR2 x 1O9 (BSNN2)/100 +

where BSRn = basestock ratio for basestock n = ~wt% basestock nl wt% total basestock in oil) x 100%
BSNNn= basestock neutral number for basestock n The results are shown in the following table, Table 1:

woss/346ls 2 1 9 3 1 2 ~

Example Comp. 1 1 Comp. 2 2 Di -,..:. ~el, ll - type PIBSAIPAM EBCO/PAM PIBSA/PAM EBCO/PAM
- treat rate 3.0 2.4 3.0 2.4 (mass~/0) VM
- type1 OCP OCP HPI HPI
- treat rate 9.8 9.0 7.5 7.0 (mass~/
P ~
- 130N treat 12.1 0 34 4 ~
rate (mass~/0) -ave. BSNN 136 145 141 158 Viscosity kV100~C 13.64 14.24 14.06 14.33 (mm21s) CCS ~-20~C) 3280 3460 2960 3120 10 3 Pa.s Noack 15 13 13.5 12 volatility (~/0) Pootnotç: 1.ocP = an oil solution of an ethylene propylene copolymer having a shear stabOity Index of 25. HPI = a hJdIU9~:nC~ d PUI~;~OU~ne VM avallable irom Shell Intemational Chemical co. Llmited as Shellvis 201.

The Examples of the invention show that an oil can be prepared using less ashless dispersant, less VM, whether OCP or the more shear stable hyd,~,ge,1d~ed polyisoprene, and with no light neutral basestock (130N) while meeting the viscosity limits for 10W40 viscosity grade oils and having o reduced volatility.

Comoarative Examples 3 and 4 and examples 3 and 4 A further series of oils were tested at 15W40 and 15W50 viscosity 15 grades. The results are set out in Table 2 below:

WO 95134618 2 1 9 ~

Example Comp. 3 3 Comp. 4 4 D;i"~. .I
- type PIBSAIPAM EBCOIPAMPIBS~JPAM E0CO/PAM '~
~ treat rate 3.0 2.4 3.0 2.4 (mass~fO) \/M
~ type2 TLA TlA OCP OCP
-treatrate 6.7 6.0 13.0 10.5 (mass~/O) - viscosity 15W40 15W40 15W50 15W50 grade B~cest~ck average 178 211 191 208 neutral no.
Viscos~ty kV100~C 13.55 14.69 18.98 17.88 (mm21s) CCS (-20~C) 3200 3290 3260 3290 10-' Pa.s Noack 10.5 9 9.5 9 volatility ~~~O) Footnote: 2. OCP = as deflned in Table 1. TLA = an oil solution of an ethylene propylene copolymer with SSI of 25, ~.u",me",L..'~ available from Texaco Chemlcal Limited as 5 TlA347E.

These results oer"u~ e that the invention enaoles iow volatility wide multigrade oils to be prepared with higher average neutral number basestock and reduced amount of VM whiGh may be beneficial in giving I0 improved diesel pe~fu",ldnc,e such as reduced piston deposits and improved soot ~ uu~ dl ICy in riiesel lubrication and reduced tu, bu~l Idl ~ur i, ,teu,oule deposits.

Claims

1. A low volatility multigrade crankcase lubricating oil meeting SAE J300 viscosity grade 5W-20, 5W-30, 10W-40, 10W-50, 15W-40 or 15W-50 comprising:

a) basestock having an average basestock neutral number of not less than 105 for a 5W multigrade, not less than 145 for a 10W
multigrade and not less than 200 for a 15W multigrade, b) a detergent inhibitor package of lubricating oil additives including an ashless dispersant comprising an oil soluble polymeric hydrocarbon backbone having functional groups in which the hydrocarbon backbone is derived from an ethylene alpha-olefin (EAO) copolymer or alpha-olefin homo- or copolymer having >30% of terminal vinylidene unsaturation and an Mn of from 500 to 7000, and c) a viscosity modifier comprising one or more polymeric additive having an Mn of greater than 20,000 and wherein the oil is substantially free of non-conventional lubricants as basestock.

2. An oil as claimed in claim 1, which is a 5W-30, 10W-40 or 15W-50 viscosity grade oil.

3. An oil as claimed in claims 1 or 2, which has a Noack volatility of not more than 17%, when measured according to CEC-L-40-T-87.

4. An oil as claimed in claim 3, which has a Noack volatility of not more than 13%, when measured according to CEC-L-40-T-87.

5. An oil as claimed in any preceding claim, which contains at least 2 mass % of the ashless dispersant.

6. An oil as claimed in any of claims 1 to 5, in which the hydrocarbon backbone of the ashless dispersant is derived from an ethylene alpha-olefin (EAO) copolymer which has an Mn of from 2000 to 5000.

7. An oil as claimed in any of claims 1 to 6, in which the polymeric hydrocarbon backbone has a degree of polymerisation of at least 45.

8. An oil as claimed in claim 7, in which the polymeric hydrocarbon backbone has a degree of polymerisation of from 50 to 165.

9. A method of reducing lubricating oil consumption in an engine, in which the engine is lubricated with a multigrade crankcase oil as claimed in any of claims 1 to 8.