Yukon Gear OK 3-QRT-CONV-A 3 Qt. 80W90 Conventional Gear Oil w/Posi Additive. Union 76 gear oil is a conventional non-synthetic 80W90 formulation designed for all types of differentials. This kit includes three quarts of oil and a bottle of Yukon Limited Slip Friction modifier that reduces noise and chatter in clutch driven positraction units and limited slip differentials.