| 摘要 |
<p>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.</p> |
