Knuckles

Stupid question and probably been asked but when i went to search just came up gear ratios and such iam probably a idiot and didnt see it, but the question i have is, is it okay to use 80w90 in the front diff and t case? please help

4Crawler

iTrader: (3)

Generally yes, consult your Owner's Manual for the specifics. Here is the data from my '85 manual:
- http://www.4crawler.com/4x4/4R_TechInfo.shtml#Fluids

Some t-cases take ATF, though.

Knuckles

well i found sources on the web that say use 75w90 in the front and t-case, but i only found 80w90 at most auto stores but as long as they are both gl-5 80w90 should work i suppose? btw i have a 1997 4runner with a.d.d.

4Crawler

iTrader: (3)

GL-5 is the most important spec. Next most important is the "90" part, that is the hot viscosity. The "80" part is the cold viscosity. The lower numbers, like "75" are thinner when cold, but not a lot of difference in 75W or 80W so should be useable. Maybe if you lived in Alaska or someplace with lots of sub-zero temps, the thinner oil might work better.

Knuckles

thank you 4crawler. i just wanted to make sure the 80w90 wouldnt ruin my front and t case if i used it and since i live in oklahoma i dont deal with extreme cold weather.

Knuckles

one last question, how do i found out if i have a limited slip and do i need to add additives if i do have one?

4Crawler

iTrader: (3)

Unless you (or a previous owner) installed one, you don't. To tell, lift both tires off the ground, spin one tire and see which way the other tire spins. If it goes the opposite direction, then you have an open diff, otherwise it is a locker or limited slip. If not an open diff, spin the tire one way then reverse it's direction quickly and see what happens. If the otehr tire stops and reverses directions with a clunk you have an auto locker. If the other tire slows and reverses gradually, then it is a limited slip diff of some type. Only if it is a clutch-type LSD will you need LSD additive. Only way to tell that is open up the diff and look at what is inside. If you have an air fitting off the diff, you have an ARB, if you have wiring off the diff (w/ an external actuator), you have an e-locker. Neither require additives.

Knuckles

thank you agian 4crawler i really do appreciate your quick answers.

rearviewmirror

I just switched my front/rear differentials and transfer case with Mobile1 75W/90 Synthetic gear lube. It's GL-5 rated which covers the "hypoid" requirement for the differentials.

The fluid in my 4WD 4Runner has now been changed at 29k and 50k. The front differential and transfer case fluid came out as golden brown as it went in, the rear however had that scorched black almost burnt look and smell to it. I am glad I changed it.

Now I'll just have to gauge how well the Mobil1 Synthetic will hold up.

mkgarrison5

if you use mobile 1 synthetic in the front, rear diff and the t-case how long should the intervals be?? i need to do mine very soon just not looking foward for it.. btw what tools do i need for the front differential??

4Crawler

iTrader: (3)

I never routinely change mine (Redline synthetic) but find every 3-5 years, I am tearing into those areas for one reason or another, so change the oil then. You'll need either a 24mm, 6-sided socket or a 10mm allen wrench depending on the type of fill and drain plugs you have.

mkgarrison5

i am thinking its the 24mm... i looked at it once and if i remember correctly it was 6 sided and a large mm at that... its a 2002 v6 4x4

jdsdj98

I've recently had my head in my owner's manual ('95 Tacoma) just for this, as I'm about to change out my entire T-case. In '95, Toyota was recommending 75W 90 (GL-3, GL-4, or GL-5) for diffs and T-cases. I wouldn't think things have changed since then or before 2002.

4Crawler

iTrader: (3)

Be sure to check the grade recommenadtions carefully. Usually GL-4 or GL-5 in the tranny and t-case (GL-4 works best in the tranny) and GL-5 (only) in the diffs.