Austin97

That works, but I like to have it sanded and swirled so there's no uniform scratches for gear oil to leak out through just in case. You'll be fine as long as it's clean, 1/4" continuous bead of the ultra black, and I always go all the way around each bolt hole, and tighten the bolts from the center out to pull it down even and I guarantee it won't leak. Unless you have a bent cover or something, but that's kind of obvious.

qdeezie

I used Amsoil Severe Gear 75w-90 and Permatex Ultra Red for my rear diff. Serves me well. If I was driving the dog snot out of it, I'd spring for the 75w-140.

far34

Im replacing the fluids so my truck will see 300K plus like i know she can. Also the cover gasket is shot and has been leaking. I got the black silicon gasket stuff also

1990-5.0-4x4

where can i get the amsoil? i've been interested in the stuff for a while, but i dont know where to get it from.

and this is kinda a dumb question, but does ford run a different weight in the front axel too? or would it not matter since i have manual hubs?

Austin97

Same weight, the hubs have nothing to do with it, the point of the oil is to keep the metal gears from frying.

Audi Junkie

Anything except Lucas, or Royal Purple





Planning a blend of 90 and 140 for my light duty driving. Not sure which proportion yet, it depends on the spec and of course how it'll be used. If I start towing, I'll swap in thicker fluid.

For GL-4 MTF fluids, we've been mixing the lighter and heavier visc oils to suit the climate and horsepower of the specific vehicle. Same principle here. MT is pretty sensitive to being stiff in cold. In near-arctic regions people use ATF as MTF, Dexron in particular (Mobil 1 ATF ideally)

Likely will go with Mobil 1 GL-5 gear oil, it's an easy choice and frankly gear oil isn't subjective like MTF is. fwiw, the newest factory MTF, like from VW, is superthin, thinner than ATF, like 6cSt.

Audi Junkie

Lucas Oil Stabilizer has ZERO additives in it, low flashpoint....just greasy slop in a $15 bottle. Use it on old barn hinges at your own risk since there's no anti-corrosives like heavily additized gear oil. Good way to water down a full formulated oil....

Also, I'm only changing the rear now, at 110k. No need to bother with the diff drives for 4wd if it barely gets used and isn't ever submerged.

Robert Weaver

I use ultra black with the gaskets never had a leak

Steve83

I'm sure he's glad to know that, 8 YEARS later.

raski

I know people who take 8 years to get motivated to get something done!