| abstract |
The present invention provides a fluid composition comprising (a) from 70 to 99.99% by weight, based on the total hydraulic fluid composition, of a readily biodegradable base oil composition comprising n (i) from 80 to 100% by weight of a base oil or base stock having a paraffin content of greater than 80% by weight paraffins and a saturates content of greater than 98% by weight and comprising a series of iso-paraffins having n, n+1, n+2, n+3 and n+4 carbon atoms and wherein n is between 15 and 35, and having a kinematic viscosity at 100° C. of at most 5.5 mm 2 /sec; and (ii) of from 0 to 20% by weight of an ester of a polyhydroxy compound, calculated on the base oil composition; and (b) a viscosity index improver in an amount of from 0.01 to 30% by weight, based on the total hydraulic fluid composition, wherein the hydraulic fluid composition has a viscosity index in the range of from 50 to 1000, and a pour point of −30° C. or below. |