differental fluid?
 

What our you guys/gals running for fluid? I'm in need of a change out and several friends/dealer tell me its special fluid and real pricey? Or can a guy put a good diff. fluid that meets the requirements or is it that special.I know my dealer is good but the labor saving will put more fuel in the tank or other things. Oh I can find my books so if anyone know volumes per diff. that would be great. Take care all and thanks, Mike in AZ

Schaeffer 293 Supreme

Been working great for 45K. Noticed a slight mileage gain, and the truck just seems to roll easier. I think the rear holds 4L (4.4qts), not sure on the front. The gaskets are reusable, so just clean 'em up with a paper towel and you're good to go.

There's nothing particularly special about our gear lube, just ensure you use a quality synthetic that meets the GL-spec (don't deviate; a GL-5 is NOT necessarily better than a GL-4) and you'll be fine. No limited slip additive required either.

Good luck!

I use mobile 1 75-90 LS works great in my limited slip diff. just use a synthetic 75-90 and you will be fine.

As long as it is synthetic and a GL-5 you're good to go.
If you are towing heavy I would say go with a 140wt in the rear. If only towing normal to light, a 90wt or 110wt is just fine. Front can be a 90wt.
Personally I use the Valvoline but any good synthetic will work.

It's only pricey from the dealer. The dealer mark up on a inferior gear oil is rediculous. The mark up could be 4x higher.

https://www.dieseltruckresource.com/...c-t282049.html

I use 85-140 gear lube and add a Lucas additive for rear ends. I have over 204K and no issues yet. Seals are still good and tight and no noise.
Guess it doesn't matter a whole lot which brand, just make sure the gl-5 is on the lable.

As noted above spec is 75W90 full synthetic rated GL5. GL5 is a rating for hypoid gears. I personally run redline but there are many choices.

Also there is a fill line stamped on the rear cover about 3/4" below the fi hole...

Since you live in a hot climate I would use 75w-140 for additional protection.

I have 50k miles on Royal Purple 75w-140 and about to change it. Picked up Walmart Super Tech synthetic 75w-140 for less than $11 per bottle.

MikeyB

Another vote for Redline here. And thanks to this thread, I looked at my records, and see that I'm very close to having to change out the differentials again! Trouble is, I have to get extra quarts, as I have a MagHyTec rear cover!

I just run mobil 1 75/90

I use the Pennzoil synthetic as well, about $43 at Advance for 4 quarts. The additive I had to get from the dealer, two bottles is what they said to put in.

5 qts of RP 85w140. Craig

xxw-140 is not necessary straight from the horses mouth (AAM), unless you consistently tow heavy in a place like Death Valley. A "real" synthetic 75w90 is all that is needed 99% of the time. Either way, whatever makes you feel good inside is what you should run.

I have run Royal purple in my truck for over 560,000 miles.

I think it cost me around 16.00 a bottle.

Cost is not an issue to the life of the differentials.


I ran valvoline for a little while in my last truck, the ford. Went through 2 rear ends for some reason. Switched to Royal purple and it stopped the rear end issues.

I've had the same experience. Other popular brands didn't do so well and RP stopped the heat and wear problems. My UOAs kept getting better and better as I went up in viscosity. I haven't found a down side with 85w140 (or with putting 5 qts in my aam) even when I lived in Co but that truck was garaged and not driven much in the winter. Craig