I am working a Ford 9" differential with freshly rebuilt Trac-Lok clutch style limited slip. I am going to fill it with Castrol 80w-90 Limited Slip oil. Does this oil have the friction modifier already added? The guy at the parts store said it does, but not sure how knowledgeable he is.
Previously I always used straight gear oil and added the friction modifier separately. However this was the only 80W90 in stock.
Previously I always used straight gear oil and added the friction modifier separately. However this was the only 80W90 in stock.