So its time to swap the juices - Front/rear/xfer case and tranny.
Is there any danger to using the same weight in the rear diff as the front?
75w-90 in both? And I have some 75w-90 LS mobil 1 , can I use this or is it no good?
Thanks

 

I've used 75w90 in the t-case and both diffs for 110K now and it works fine. I think the M1 stuff you have has limited slip frictioners in there but AFAIK, that's ok (most synths do). I don't use stuff with the frictioners just because I've heard it's hard on the seals for my ARB locker, but if you're stock I think it's perfectly fine. Probably not the best for people with elockers though.

 

75-90 is what the owners manual says.

 

Thanks Brian.
Scuba, yes you are correct for the front diff and xfer case, but FSM calls for 80-90 in the rear diff.
I am gonna pick up some 75-90 in the morning and get started.
Side note about the tranny - has anyone attempted to use a light gear oil in an auto tranny before?
Thanks!

 

Definitely not a good idea. The A340F is extremely reliable and also extremely picky about fluid. Only use what the manual calls for (Dexron II or higher in my '97). Stuff like synth Amsoil Universal ATF is ok, but whatever you use, it must say that it is compatible with whatever level of Dexron yours calls for. I recommend the Amsoil ATF, that's what I use and mine shifts perfectly w/ 200K on it.

 

There is no risk in using 75-90 in the 4runner rear with an auto. All the aformentioned synthetic gear oils will do fine. I've used Mobil 1 75-90 all around with good results.

If you want to stick to the 80w-90 weight, try and find Chevron Delo Gear ESI 80w-90. I am using it now thanks to the leaking rear inner seal and am extremely happy with it. The problem is you cannot find it at Autozone, Pepboys, etc. I found it at a local Chevron oil distributor in NC who was willing to sell me individual quarts. Most want you to buy at least a case. But it is less costly per bottle than synthetic. Shell Spirax 80w-90 is also good.

 

I used that Mobil 75W 140 in the rear. There was a thread about it a month or two back if you take a look. I do plenty of towing my trailer around, especially in the summer and wanted something a bit more substantial.

 

for the Auto Tranny fluid I can confirm that DEXRON is up to roman numerals VI -meaning DEXRON 6, and they are backwards compatible.

If you want to keep your auto tranny happy get Dexron 6 and if money is burning a hole in your pocket then go full synthetic while at it. Consider flushing that auto tranny frequently if you want to keep it.

keep the dreaded strawberry milkshake at bay by changing out the radiator every 7-8 years or so-or installing an external tranny cooler or both. Radiators are cheap compared to a new tranny. About a 60 minute job to swap in a new KOYO radiator on your 02 Sport Runner.

 

I just use cheap 80W90 in the rear and front diffs. Redline 75W90 in the transmission and 75W90 in the xfer case.