75W80???

[oldhp]

Never heard of this before. My 2024 GMC Canyon 4X4 takes this GM 19433379 75W80 full synthetic gear oil in rear differential. This for gas mileage??? I thought 75W85 was bad. Thinking of just using Redline 75W90. I have a open rear differential. Front diff takes 75W90 and the transfer case takes Dexron IV. Your thoughts please.

 

[ripcord]

I'd use the 75W90 and never look back. CAFE scores can shove right off, LOL.

 

[Snagglefoot]

Yes, the new owners manuals for these trucks do not list the required lubricant and you need to have the dealer run the VIN. The 1500 models use 75w80 but the 2500 and 3500 units use 75W90. You can chalk this one up to gas mileage issues. If you like, change it to 75W90 synthetic. There is no drain plug on the 1500 (AFAIK), so you’ll have to loosen up the bolts on the diff and crack the seal. Some are comfortable just tightening up the bolts again. If you want you can take the cover off and clean the magnet to get rid of any of the early metal wear.

The transfer case is a Magna Powertrain (MP) and specs Dexron VI. Magna has been suppling GM with truck transfer cases for almost 20 years and it has always spec’d Dexron VI (Dex VI). The 2500 and 3500 also get beefed up versions of MP transfer cases but still use Dex VI.

 

[ka9mnx]

I've had vehicles that required 75w-80. They got 75w-90. My 4Runner calls for 75w-80. It has 75w-140 in it.

 

[4WD]

I've had vehicles that required 75w-80. They got 75w-90. My 4Runner calls for 75w-80. It has 75w-140 in it.

Same - with three 4WD’s - I find it annoying they can’t even spec the same fluid front/rear … GM’s get Delvac 1 - Amsoil SG in Jeep …

 

[Kira]

I find it annoying they can’t even spec the same fluid front/rear

I had that thought too but figured they must've had a reason.

 

[4WD]

I had that thought too but figured they must've had a reason.

In the case of GM or other “domestics” - AAM might spec the fluid and override what Eaton says - or the builder can override both - or any combination with 4WD …

 

[racer12306]

I find it annoying they can’t even spec the same fluid front/rear

I had that thought too but figured they must've had a reason.

I agree, however when the front is thinner than the rear, I understand that a little since probably >95% of the time the front is just free spinning.

For the record, my Ram has 75w90 in the 75w85 spec'd front.

 

[oldhp]

Changed to 75W90 in rear open differential. I could not believe how thin the cold gear oil drained out. In went Redline 75W90. It's just a little GM 10 bolt open. The guy's on GMC Canyon site are all about staying with what GM says. I'm pretty sure I'm going to put 80W90 conventional in the front simply because it clings better. But I do have some Redline 75W85 left over. I'll cross that bridge later.