I have a 1993 Ford F-350 4x4 with a 3:55 limited slip rear end. I'm trying to determine what type of gear oil I should use for this. Is regular 80-90 gear oil ok or do I need to buy some special gear oil? Thanks, Tom. Also, would the front end take the same? How often should the transfer case oil be changed and is this totally separate from the E 4OD transmission.

 

Ford Specs 80W90 (XY-80W90-QL). You need to add friction modifier for your LS.

I do know that ford changed to 75W140 for the 8.8 axle in the explorers in later years for better longevity. So 80w90 should be fine, 75W140 would be better.

Ford speced (F1TZ-19580-A) which is definded as "4x4 gear oil". I think this is a straight 80 if I'm not mistaken. Ford has also updated this to 75W140.

Haynes says to change the fluid in the transmission and transfer case at 60,000 miles. I would doubt the T-case really needs to be changed that often.

 

If you're interested. Here is what Dana has to say about it:

http://www2.dana.com/pdf/5324.pdf

scroll down to page 3.