Getting a new. Used. 1983 Toyota 4x4 pickup.
what fluids can I use in the diffs, trans??
I have supertec gl-5 synthetic. Can I run this in all the diffs???

 

You can pretty much run whatever you want. I think the manuals call for 75w90

 

I can never remember which is which, but I think, rarely, but I do think once in a while, that you're supposed to use GL-5 in the transmission and transfer case, and GL-4 in the pumpkins. Assuming a manual tranny, of course.

Don't forget to lube up the u-joints, and the double cardan real good. Keep them lubed, too. My 87 4Runner still has the factory joints in, and they're still in good shape. But I lube them often.
The factory joints come with little bolts in the holes where the grease goes. Replace them all with grease-zerts. Well worth the slight cost, and the time involved. There's more of them you might think, too. You'll need a lot of zerts.

Have fun!
Pat☺

 

It's GL-4 in the manual tranny. GL-5 in the differentials.

GL-5 is often too slippery for old syncros.

 

I apologize. I got it bass-ackwards.

Again, my apologies.
Pat☺

 

Personal opinion - Redline MT90 for the trans. Really helped in mine.

 

+1 for the MT 90 in the trans. If you don't like the price, you can use any GL-4. Sta-Lube has it.

 

In Arizona, (Phoenix and Tucson), you can get straight GL-4 gear oil in 5 gallon pails from Arizona Petroleum.

Their Rugged Euro 75W90 has given good service to me.

I also use their Silver State synthetic GL-5 gear oils in my diffs.

Same products in Denver (Colorado Petroleum)