Hey guys, I am putting a limited slip diff in my Ranger. Can I used a synthetic 80W-90 gear oil with my limited slip? I have a 4oz bottle of the motorcraft friction modifer to use already. I have heard the the synthetic gear oil (like Royal Purple, Valvoline SynPower, Mobil 1 ect.) have friction modifier in them already so I dont want to have too much friction modifier in there and make my l/s too loose. Also, is 3-4 quarts enough for the 8.8? Thanks.

 

I'd use 75-140W Royal Purple (etc) or use conventional with modifier. I dont think your gonna use more then 2 bottles of gear oil.

 

Mobil1 already has it. No extra needed.