A lubricating oil composition contains a base oil (A), a zinc dithiophosphate (B), and a sarcosine compound (C), the composition having a content of the sarcosine compound (C) of more than 0.05% by mass and 0.40% by mass or less based on the entire amount of the lubricating oil composition, and satisfying requirement () or (): Requirement (): when the content of the sarcosine compound (C) is more than 0.05% by mass and less than 0.20% by mass based on the lubricating oil composition, one or more phosphorus compounds (D) selected from an acidic phosphoric acid ester (D1) and an amine salt thereof (D2) are optionally contained; Requirement (): when the content of the sarcosine compound (C) is 0.20% to 0.40% by mass based on the lubricating oil composition, the phosphorus compound (D) is contained in an amount less than 0.50% by mass based on the lubricating oil composition.

Metal working fluid decontamination apparatus (10) includes: an intake arrangement (40) for metal working fluid (42); a pump (16) for providing, in use, flow pressure to the metal working fluid (42); a decontaminator (50) for reducing contamination in the metal working fluid (42); and an outlet arrangement (34) for the metal working fluid. The metal working fluid (42) is a fully synthetic metal working fluid, which comprises water and a water soluble synthetic concentrate which does not comprise oil.

Lubricant compositions may provide corrosion resistance, oxidation resistance, and reduced wear for hydraulic systems. A lubricant composition may comprise an ashless dithiophosphate in an amount sufficient to provide a concentration of phosphorus ranging from 10 ppm to 250 ppm to the lubricant composition, a metal dialkyl dithiophosphate such as zinc dialkyl dithiophosphate (ZDDP) in an amount sufficient to provide a concentration of phosphorus ranging from 50 ppm to 1000 ppm to the lubricant composition, a corrosion inhibitor comprising an alkyltriazole derivative in an amount sufficient to provide a concentration of nitrogen ranging from 0.75 ppm to 100 ppm to the lubricant composition, and a major amount of a base oil.