Diff Fluid Change - 3.4 V6 4x4 w/locker

Run MT-90 in the tranny and you'll be a very happy camper.

My truck had the fluids changed when I bought it but they threw 75-90 GL5 in there and it wasn't shifting great.

I think MT-90 is one of the few GL4s still out there and I'd rather live on the safe side and not have the GL5 eat my synchros.

 

Oops I meant transfer case

 

X2 on the MT 90. I have used this on my last three yotas 81,88,91 and it works like a champ for the trans. Will be doing the taco soon.

Amsoil is good stuff as well for the trans and diffs.
Mobil one and valv syn stuff is good as well, and easy to find.
75w90 is great for colorado because of the cold winters.

 

I'd run MT5 in there as well...

If you ever blow a seal, better to have both gl4 than try mixing.

Granted, you're going to have bigger problems than mixing oil but still.

Synthetic GL4 in Tranny and xfer, synthetic gl5 in both diffs

 

I hope no one is planning on getting that close to a seal.

 

Great, just as I was about to go out and buy all the fluids... GL-5

$30 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90 for the tranny, transfer case and differentials.

 

turn that frown upside down, meester!

 

Should I get the MT 90 for the transmission and transfer case?

I have no idea what GL-4 vs GL-5 even means.

 

This will help explain things.

http://en.wikipedia.org/wiki/Gear_oil

Use what is spec'd in the manual.

 

My 2003 FSM calls out API GL4 or GL 5, SAE 75W90, 1.1qt. on the transfer case. Fill to within 5mm of the bottom lip of the fill hole.

For the transmission, it calls out the same type, 2.3 qts.

 

GL4 and GL5 are designations for oil.

GL5 has a higher sulphur content that is not great for brass synchros and while it isn't necessarily proven to do so, makes shifting more difficult due to different modifiers in both oils.

As your M/T and transfer case share a seal, it is a safe idea to run GL4 specific oil in both of them, Redline MT90 is a good choice and one of the few specific GL4s still available.

As both the front and rear diffs have hardened steel in them and they are merely transmitting power, a GL5 (noted for its good shear properties) synthetic will do you just fine.

So to recap:

Manual Tranny and transfer case get GL4.

Both front and rear diff get GL5.

Both come in weights of 75-90 unless you decide to run different weights... In which case I can't help ya

 

Or just run a decent synthetic in all of them.

 

If I lived in a cold area I would run the 75W90 or Amsoil severe.

I'm in FL where we never go below 35 degrees so I run dino 90W in FD TC RD
I will change it every 30K miles on my asphalt queen

 

Here's what I got:

Royal Purple for the transmission and transfer case (

$30 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90). It was on sale for $15 a quart.

Valvoline SynPower synthetic for the front and rear differentials (75W-90)

This should be okay, right? With the rear locker.

Next....

I bought one of those hand pump things to use to fill the diffs, transmission, etc.

My question is... how am I supposed to know when I've used 0.3 quarts and/or the fluid is 5mm from the bottom of the fill?

 

Stick your pinky in and feel. Getting exactly 5mm isn't super critical. You just want the fill level to be no greater than 5mm below the fill hole. Filling to the bottom of the fill hole will work if you want to do that. Diff Breather FTW!

 

Check out the FSM picture:


The top of the fill has to be less than 5mm from the bottom of the hole.

 

Thanks Tom.

Last question: In your opinion, am I alright with the gear oils I selected? See my previous post.

I just dropped over $150 in fluids, just want to make sure I'm all good before I open them.

 

I'm not much of a brands guy. If they say they are

$30 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90 and for use in GL-4 or GL-5 applications, you are good in my opinion. Synthetic makes it even better.

 

You're good to go

Just remember to pull the fill plug before the drain plug!

 

Thanks.

That much I do know. (only because I read it on this forum. If I hadn't I would have definitely pulled the drain plug first )