[75BRONCO]

So my local Auto Parts store does no have straight 90w fluid which is what the FSM calls for. THey do have a 75-90w synthetic $$$ or a 80-90w fluid. Is one better for this application or is a preference thing or should I hunt down straight 90w?

Thanks for any input

[Tools R Us]

The 80-90w fluid is the newer spec, will work fine.

[rhyary]

What about the Synthetic 75-140?
Pep boys had only that kind. Will it work in the LX450 diffs?

[badmuthatrucka]

More than likely, NO. It would probably end up being too viscous, or thick, for driving around. Could cause premature wear, overheating of the diff, etc.

I always use 75w-90 or 80w-90 plus some Lucas oil Stabilizer. Always use what the manufacturer suggests, or the closest thing to it. They suggest it for a reason.

[rhyary]

I am not running anymore what Toyota designed. I have a 4.88 and different tires. So not sure, which is the source of my question, if what the manual says is necessary the best for my situation.

I do have a bias toward havier oils. I run Mobile one 15-50 in the engine.

[Lka1988]

When I installed my locker, they said to run 85-140 to break it in. No issues with that.

Well, I broke it in by running my truck through a 3-foot deep puddle with slick mud at the bottom...

I changed the oil back to regular 80W-90 due to water getting in, still haven't had any problems.

[mtrdrms]

the 75-140 is super thick. I would go with the 75-90

[UCBerzerkeley]

Originally Posted by badmuthatrucka

More than likely, NO. It would probably end up being too viscous, or thick, for driving around. Could cause premature wear, overheating of the diff, etc.

I always use 75w-90 or 80w-90 plus some Lucas oil Stabilizer. Always use what the manufacturer suggests, or the closest thing to it. They suggest it for a reason.

did the manufacturer suggest lucas oil stabilizer too?

[Kernal]

I use Mobil 1 75W-90 (autozone) in the transfer case and rear diff, Walmart brand semi-synthetic 75W-90 in the front diff until I replace the front axle seals.