75W-90 or 80W-90 Diff Fluid

I have a 2001 2.7L 4WD 4 speed automatic (3RZ-FE Engine). I am going to do the rear diff, front diff and transfer case fluids.

I am confused about using 75W-90 or 80W-90.

The mechanic in these two videos uses 80W-90 in the rear diff, but then uses 75W-90 in the transfer case. Rear diff video. Transfer case video.

Is there reason to use 80W-90 in the rear diff and use 75W-90 in the transfer case and front diff?

It seems like a lot of people just use 75W-90 in rear diff, front diff and transfer case. It would be nice to just buy a bunch of the same fluid for all three locations. Any reason to not use 75W-90 at all three locations?

 

Not a lot of difference, just grab whatever. I personally used 75w90. The transfer case uses GL4 fluid, not GL5 like the diffs do. Use Redline MT90 for the transfer case.

 

I haven't seen anything that says the transfer case needs GL-4 and not GL-5... I know that manual transmission fluid needs to be GL-4, but I have an automatic and I'm not doing the transmission fluid right now anyways.

 

Manual trans and transfer case takes GL4.

 

I work at a Toyota dealership and we use 80w-90 for differentials and transfer cases.

 

There's no reason to use 80W90, 75W90 is identical but better viscosity in the cold.

It's the same reason 10W30 is dead, 5W30 killed it. There's no reason to chose the higher W rating.

Either one is fine, but if it gets even remotely cold in your region, 75W90 is the answer.

 

Thanks for the explanation Bishop84. So that goes for rear diff, front diff and transfer case?

Also, any thoughts on what Nano909 said about the transfer case needing GL4 fluid (Redline MT90)?

 

GL4 is ideal for Tcase but not required, people make a big deal about it but it won't case the tcase to fall out, it's just not ideal for the brass I believe.

I've been using GL5 on Toyota tcases for 20 years now. Including many of my own. Same goes for manual transmissions. Buy GL4 if you can find it.

My dealer uses 75w90 GL5 on all standard axles.

 

For what it is worth I have been using 85-140 Gear oil since the mid eighties .

I got a deal on a 55 gallon drum.

It never gets that cold in Eastern Pa not weeks below zero .

Never any issues that I have ever discovered.

 

Thanks so much for posting that table. Do you know why they call for 75W-90 for the front diff and t-case, but 80W-90 at the rear diff? I know I'm probably splitting hairs here, but just very curious.

 

I don't but it's toyota, if they say it works then good enough for me.

 

I use 80w90 in the rear diff as instructed by Toyota and 75w90 everywhere else. Everyone has their preference but I stick with the book.