Gear Oil
 

I have an F250 w/ the Ford 10.25" rear end w/3.55 gears and a detroit locker installed. I need to change the gear oil and was wondering what weight and kind I should use.
In the truck manual it says to use XY-90-QL or EOA2-19580-A with spec. ESW-M2C105-A. Does anyone know what weight this oil is (not stated in the book)? Also would it be better to use synthetic or synthetic blend oil over regular oil?
Does anyone know if the cover for this rear end has a gasket or do you just silicone it up?

Your owner's manual will list the correct rear axle lube. It is probably 85W-90 gear oil - same as listed for my '95 F250 . A synthetic equivalent would be the best one to use.

Lou Braun

I just filled my motorhome rear end with Redline 75w90. It cost only $7.99 a quart for this full synthetic lube. They have a no slip version that might work with your Detroit Locker. Call their techs and tell them what rear end and about the locker and see what they recommend.

What rear end does your truck have? My owners manual just gives the ford part and spec #'s for the gear oil. I don't know why, but it doesn't have the weight of the oil to use anywhere in it.
Thanks.

The 90 in XY-90-QL means SAE 90. Ford is really bad about this. They want you to buy everything from them. 75W-140 synthetic is the current factory fill for the 10.25 Ford/Sterling, but I would ask the Detroit Locker people for a recommendation.

Jim

I have 85w-140 in my detroit locked rear, I prefer it thicker to cool down some of the clanging from the detroit