Gear Oil

I know there’s existing threads on this topic but I wanted get some fresh opinions.

Owners manual suggest 75-85 GL5 for differentials. I’ve noticed that most of the local auto parts stores carry 75-90, would this be ok? I prefer to buy locally rather than mail order whenever possible.

Second question pertains to mineral vs synthetic gear oil. A quick Google search list many advantages of synthetic. Has anyone here had gear oil leaks related to using synthetic gear oil vs mineral based?

I’ve read that some gaskets and seals may not be compatible with synthetic lubricants.

Obviously our engines are designed for synthetic but I’m not so sure about the gear boxes.

Thanks

 

Spent more time searching and answered my first question. Substituting 75-90 for 75-85 is acceptable. 75-85 is not as common.

 

I’m doing my fluids here soon. Dealer stated 75-90 works for the diffs and transfer case. Synthetic all the way.

 

Perfect, thanks. Yes from what I’ve read, that’s the way to go. Which is good because that’s mainly what I’m seeing on the shelves at the local auto parts stores.

 

75W-90 GL-4 or GL-5.
See posts 13 and 24.
https://www.4runners.com/threads/wo...ead-of-the-70-toyota-fluid.12858/#post-222929

 

Thank you for locating the appropriate thread.

 

Redline makes 75W85 Gear Oil:

 

Ravenol makes 75W85 and is available on Amazon. They also have a 75 weight that is acceptable for the transfer case.

That said, I have synthetic 75W90 in all 3.

 

I used 75W90 in my Tacoma without issues. It made it 135K miles before a red light runner totaled it.

Any off the shelf oil of the correct viscosity will work fine. The problem with the synthetic classification is that the term is pretty loose in its requirements.

 

I think seals leaking because of synthetic was a thing 40 years ago.

I've run all syn in my 136k '13 for 50k miles now with no leaks. 75/90 in diffs & Tcase, btw.

 

Excellent, that’s good to know.

Thanks

 

Today I got the transfer case and rear diff fluid changed. Do front differential tomorrow?

Just wanted to point out that the new Vavoline gear oil squeeze bag is fantastic! Life changing.

It made the filling process so much easier.

24k miles, a little early. The drained transfer case oil looked clean. The rear differential oil was gray but not bad and drain plug magnet had very little debris.

 

The squeeze bags seem like a real win/win. Easy to use, and less waste. Not sure why more products haven't gone this route.

 

Front differential is done. I may have overfilled a bit. With the diff drop it changes the fill port hole a little.