A polyol ester suitable for use as a lubricant or a lubricant base stock has a kinematic viscosity at 40° C. greater than or equal to 200 cSt and a viscosity index of greater than or equal to 100. The ester comprises the reaction product of (a) a polyhydric alcohol component comprising at least 50 mole % of penterythritol, and (b) a carboxylic acid component comprising: (i) at least one linear or branched monocarboxylic acid having 2 to 7 carbon atoms; (ii) at least one branched monocarboxylic acid having 8 to 15 carbon atoms; and (iii) at least one polycarboxylic acid having 2 to 8 carbon atoms; wherein the ratio of the number of acid groups derived from the monocarboxylic acid(s) (i) to the number of acid groups derived from the monocarboxylic acid(s) (ii) is between about 0.9 and about 1.1 and the number of acid groups derived from the polycarboxylic acid(s) (iii) is between about 15% and about 25% of the total number of acid groups derived from the carboxylic acids (i), (ii) and (iii).