I like the Redline Heavy Weight shockproof gear oil, it has a 75W250 rating and really clings to gears:
http://www.4crawler.com/4x4/index.sh...ntheticGearOil

 

Yeah misterzee has been using Amsoil religiously since 1979... Except when he doesn't

 

I agree that a heavier oil is better for MOST offroad applications.

NOT for ARB differentials.

I have been running conventional 75w90 in my ARB'd diffs with ZERO issues. So have several others I know.

TC has been running the readline heavy weight stuff, in both of his ARB'd diffs, and it has ruined several sets of o rings in the rear, AND jammed up his front locker, which we just finished fixing.

We pulled the front locker completely apart, and found redline in EVERYTHING. It had gotten in and jammed the pressure plate that actuates the locker.

Simple cleaning of the locker fixed the problem.

I will not run anything heavier than 75w-90 after seeing that.

In an auto locker situation, the redline stuff would be PERFECT, as it would really help with noise, and overall diff care.

 

Awesome! and thanks for the leads to find it!

 

I've had RL Heavy Shockproof in my front and rear ARBs since I first got them about 9 years ago. No problems at all, they still lock and unlock fine. These are the older/original design units, maybe the newer design might be different.

 

I was surprised to find that Redline Oil wasn't perfect for an auto locker. My Aussie Locker is louder with the Redline than it is with cheap 80W90. I bought the Redline because their MT-90 was brilliant in my transmission and I thought that Heavy Shockproof gear oil make the Aussie Locker quiet. It doesn't. I'll probably be moving to a 80W140 or something. Mechanically, Shockproof is probably brilliant, it just makes more noise than 80W90. The front diff will likely get the SHockproof, because that stuff is expensive.

Is the fuel economy drop I will experience with 80W140 likely to be noticeable? Redline Oil's website says I will likely experience a 0.5% decrease (which won't be "noticeable"). Anyone have any experience with this?

 

you may notice a small difference in gas mileage if it were dino gear oil but synthetic, i doubt it..

 

you said it was a 250wt, to me thats way way too heavy and thick.. i can see how he had issues. 140wt is perfect for most of these guys who live down south and or tow, or wheel alot.. 140wt in synthetic would even be better for cold temp protection.

i am going to mix 50/50 75w90 and 75w140 amsoil severe gear. that will get me close to the 75w110 thats highly recommended. i dont wheel often at all but i do pull a 21ft bass boat and camper (not at the same time of course) quite often

 

Im still using walmart branded gear oil, 80w-90 GL5 oil. No issues at all.

 

supertech right? how many miles on the truck? how many miles between changes? just curious

 

My Mobil1 75/140 is doing great...no difference in mileage.

 

i use canadian tire 80w90 gl5 for 4 quarts its 15 bucks canadian!!!

 

I'm pretty set on 80W140 and oil that heavy sounds like it needs to be synthetic.

 

So I have heard that a conventional oil actualy is better in diffs. Is this true?

 

under sustained high temp usage, conventional oil breaks down faster than a true synthetic oil.

I use Red Line 75W90 in my diffs and transfer case

 

Check this out then.
https://www.amsoil.com/products/gear...hitePaper.aspx

 

I think you need a PhD to figure out the results. It sure looks like some excel in some tests and don't do so good in others.

 

And the study was commissioned by Amsoil, which makes the whole thing pretty suspect, IMO. A key tenet of scientific research, say in medicine, is to ensure that those who commission and conduct the study do not have any inherent conflicts of interest. That was certainly not the case here.

 

Amsoil submitted the oil to an indepenent lab to be tested with all others, if they fail they fail .
The easiest way to see if any of your oil is performing as it should is to send it in for a UOA. Very few people do it tho they just look at it or feel it and think its ok, or go on hearsay and big money marketing and commercials. I have my oil tested and Amsoil is works for me and has for years thats why i became a dealer plus i get it cheaper. If i didnt i would run something else and test it till i found one that works. From what i have found people love it or hate it or just dont know about Amsoil. Im just trying to help people get it on here at cost so they dont pay full price for it.

 

East coast gear supply highly recommended running Lucas 85w-140 during and after break-in of their new/rebuilt differentials. I commonly was getting combined 20-23mpg running synthetic
80w-90. After switching to the 85w-140 when replacing new diff and replacing axle bearings/seals, I have not since seen 21 mpg. I am switching back to a synthetic 80w-90. I run Redline MT-90 in the tranny but intend to run valvoline syn power in the rear, as that was what I had prior to replacing axle bearings. Anyone else run Valvoline gear oil in the rear/front diffs?
Endless head scratching with this truck.