SPLAT

I have 2 F150 trucks and decided to change the rear diff oil... I can't get the same answer from any two sources as to what fluid/oil to replace it with!

When I rotate one tire the other opposite tire rotates in the opposite direction, so I assume it is limited slip...

I have a gallon of GL-5 80W-90 non synthetic and a 4 oz tube of Sta-Lube differential friction modifier... but I can't tell if it is the correct materials

Any help is appreciated

Just call me Sean

iTrader: (1)

It is not a limited slip or the tires would have spun in the same direction. Just the 80-90 is fine.

Nitehawkjr

It uses 90w in the rear with 4oz. of modifier just make sure the oil is for limited slip if that is what you have but i don't think it is with the rotation you described.

lksmith95

i think Sean is right, but look on the inside of your drivers side door, next to the latch and there should be a chart, look under axel code and post it on this thread what it is and sombody can tell you if its limited slip or not.

SPLAT

OK, cool... I DOUBLE CHECKED AND TIRES DEFFINATLY ROTATE OPPOSITE DIRECTIONS

The code for the axle inside the door is 19.

Thanks for the help people!

|SkidRow|

Code 19 is 3.55's which are Limited Slip, but the PO might have changed them.... further investigation may be required here

ndnJedi

Code 19 is 3.55, but it is not LS. I have code H9 which is 3.55 with LS. Just straight gear lube will be fine in your example.

5.5 pints(2.75 qrts 2.6 litres) should the capacity +/- 0.3 of a pint.

When I get around to changing my rear diff oil it is gonna get some Royal Purple as that is synthetic and doesn't need any friction modifier added.

fordtrucknut

really just pull the cover and check it, you should check the ring and pinion gear teeth anyways for chipping. when you change the fluid.

this is LS, limited slip, posi, trac lock or what ever you want to call it.


this one is an open diff, one wheel wonder. single tire eater.

95stepside

Little tidbit o information for y'all, any ford truck 1959 to present with a letter in the axle code is limited slip

kc0rey

Correct! Assuming no modifications have been made