Hey guys, ive got a 99 2wd F150 and it has 113,000 miles on it and the rear end has never been serviced. I was wondering what oil should be put in it and if there is any other kind of fluid that should be put in it because of the posi? Thanks for the info.

 

There should be 2 tags on your diff cover. One has the stock number, gear ratio, etc. The other one says what fluid to use. I can't remember what mine says so just take a look. As far as the LS, you'll have to add LS additive. I have had a lot of trouble finding auto part stores that carry this. The only one around me that carries it is Autozone. You can also buy gear oil with the additive already in it. I beleive that Royal Purple is one of them. Somebody else with a little more knowledge on the subject will give you more info.

 

alright thanks. i think im just going to go down to the ford dealership and buy some of the LS additive. thanks for the help though.

 

Most rearend now use the 70/140w synthetic fluid. The dealer charges about U$26 a bottle for it - you need three.
Walmart and some autostores have it now too, since it is more common, for about U$10 bottle.
The limited slip additive is cheap at the dealer.

Fritz

 

Capacity is 5.5 pints except with the 10.25" ring gear, that one is 7 pints. Get your LS additive from the dealer (C8AZ-19B546A) and go find an Amsoil dealer - their 75W140 synthetic is $13.75 a quart.

 

alright thanks. i went to the dealership today to get the limited slip additive but im going to go somewhere else for the oil. thanks a lot for the info.