[jagarra]

Since this thread started with a power lock differential subject, I will ask a question about them. I removed the differential cover to see how much gunk had accumulated back there, I was surprised to see really clean 90 weight and no gunk to speak of. I saw a tag on one of the cover bolts, I was hoping it was the gear ratio, but no, it said to use power lock lubricate in this unit. Seems this truck has that rear end. Now in my maintenance manual it says to add some power lock lubricant. Well my Valvoline 90 wt. says it is for limited slip applications, is this good enough or should I go buy some of the additive stuff they sell??