| abstract |
A polymer suitable for use as a viscosity index improver for lubricating oilncompositions, which is at least one, at least partially hydrogenated linear or star-shapednrandom copolymer of isoprene and butadiene, in which at least 70 wt. % of thenbutadiene is incorporated into the polymer as 1, 4 units and the weight ratio ofnisoprene addition product to butadiene addition product in the copolymer is in a rangenof from about 90: 10 to about 70:30. |