| abstract |
High performance engine oils and other liquid lubricants comprise a liquid lubricant basestock of low viscosity from 1.5 to 12 cSt (100C) with two dissolved polymer components of differing molecular weights. The basestock is preferably a single PAO or blend of PAOs with a co-basestock component which is preferably an ester or an alkylated aromatic of comparable viscosity. The lower molecular weight polymer is highly viscoelastic in character and is preferably an HVI-PAO; this component in the lubricant which provides unexpectedly high film thickness and unexpectedly good wear protection under conditions where the second, higher molecular weight polymer may lose some or all of its thickening power. The use of the highly viscoelastic low molecular weight polymer in combination with the higher molecular weight thickener enables the production of very widely cross-graded engine oils, especially oils with a low temperature grading of 0W or better. Oils with cross gradings of 0W20, 0W30, 0W40 or even more widely cross graded, for example 0W70 or higher may be achieved. |