this invention relates to shear stable multigrade oils for crankcase lubrication of gasoline and diesel engines which oils are substantially free of viscosity modifier additives and comprise a detergent inhibitor package of lubricating oil additives , which package includes 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 copolymer or alpha - olefin homo - or copolymer an m n of from 500 to 7000 . such multigrade crankcase oils without viscosity modifiers are more economical and may provide better diesel performance and seal comparability . the oils are also substantially shear stable and may be used in turbocharged engines and racing engines , with reduced mechanical breakdown of the oil .