This invention relates to mineral oil based gear oils and transmission fluids which comprise a major amount of a mineral oil having an iodine number of less than 9 and where at least 55% of the saturates are aliphatic, and gear oil or transmission fluid additives. In one embodiment, the invention relates to a gear oil or transmission fluid composition comprising a major amount of lubricant basestock and at least one functional additive wherein a major amount of the lubricant basestock comprises a mineral oil having an iodine number of less than 9 and comprising at least 45% by weight of aliphatic saturates. These gear oils and transmission fluids have good viscosity and oxidation properties.