Castrol Syntrax Universal 80W-90 is a part-synthetic SAE 80W-90 multipurpose manual transmission and final drive lubricant. It is particularly recommended for use in highly loaded final drives and differentials of commercial vehicles where API GL-5 performance is required and it carries a number of approvals. Additionally it may be used in synchronised manual transmissions requiring API GL-4 or GL-5 fluids.