Wow. I just completed changing my diffs this weekend. I can't believe I was thinking about paying someone to do that for me. It was easier than changing my oil. Less messy too. Thanks all for the advice and pointers. The truck feels like it moves smoother now too with that good 'ol purple stuff.

 

For all of you that are using royle purple I would change that out right now. I have seen a comparitive test report and that stuff is NOT good, It failed alot of the tests. I am not a fan for royle purple, Delo 400, shell rotella, or lucas, in anything.
Here is the link to the amsoil web page and the study of gear oils download it and read it, its well worth the seat time.
http://www.amsoil.com/products/gearl...hitePaper.aspx

 

Like the man said, use GL-5 FULL SYNTHETIC oil. Don't go cheap here. This is an extreme pressure application. I would not consider going to a heavier oil unless it was completely broken in and then only if maximum loads were being towed.

 

My differentials were a lot cooler when towing after I switched to Amsoil SG 75w-140. It is an easy job, no need to pay someone to do it.

Here is an interesting firsthand study I did. I have a John Deere utility tractor with front wheel assist that uses planetary gears to drive each front wheel. I have been running Amsoil 75w-140 in them since it runs a lot in the winter and those hubs never get very warm unless you are pulling hard for a long time or running them up and down the road. (I do neither in the winter). This summer one of the seals on one side went out and the JD mechanic changed it and refilled it with the JD 85w-140 non synthetic. When I was hauling hay home this fall I had to drive the tractor to a field about 6 miles away to load hay. After the drive just for fun I felt the side that had Amsoil in it and it was barely warm. On the other side it was a LOT warmer. I thought this was kind of interesting.

 

I did some quick looking and the DMax guys are saying that GM recommend 75/140 synth when towing heavy. At least on the 1 thread I looked at. I think its more about using quality oil than what weight though.

 

Alright you convinced me. Everything in my truck has Amsoil now.

 

I just serviced my rear diff. and used 75-90 Royal Purple. It can't be that bad..

 

I only have 14k on my rear diff oil with 75/90 severe gear Amsoil and i'm NOT impressed. The oil looks terrible. It should look pretty much brand new still, but I am going to get it changed ASAP because it's so bad that i'm actually worried. Haven't decieded yet what's going back in, but I am less impressed with Amsoil all the time.

 

My walmart 75-90 came out looking pretty good this afternoon. I hope the royal purple holds up as good as the wally world did...

 

Amsoil is crap. I personally feel that the only reason people like it so much is that anyone can become a "dealer" to try and sell the crap.

 

I liked how my truck started in the winter with it, but it could just be that it's synthetic at any other one would yield me the same results. For chaincase oil for my snowmobile I was impressed that it's flowing point didn't change when it was extremely cold like another brand though.

I haven't checked my tranny or t-case or front diff yet, but I sure as heck hope they look better, I just did them all last summer, cannot afford to replace all the fluids just yet

 

I use Royal Purple 75W90 in both diffs, and will likely use it again. It's easy to find nowadays, but man their prices have really skyrocketed and never came back down. Specifically, their diff fluid is now pretty much through the roof. I got mine for $9.99, and now I see it for $17.99. But it's certainly easier than trying to find Amsoil. Too much trouble if you have to order it and wait and pay shipping, plus their outrageous prices.

And why is a bottle of diff fluid way more than a bottle of motor oil, or ATF? Isn't it just oil? Oh wait, I know. It's because you don't change diff fluid that often, so the scheister oil companies want to get their money out of you one way or another.

 

So far all of the Amsoil products I've used are great. I think its nice that the engine oil I drain out still has a TBN of 10 after being in the engine for 367 days, 7K. The ATF so far has held up but I have not looked at the gear oil in a while so I guess I should do so, but I don't think it will be as bad as the factory junk I drained out that was milky gray and drained out like 10wt oil an that is after it has been setting for 6 hours in a 34 degrees garage.

As for the cost of Amsoil products my local Farm store has Severe Gear 75/90 for $12.95, ATF for $10.75 and 15w40 retails for $31.05 and these prices are cheaper then what NAPA wants for Royal Purple products.

My self I never have to order my Amsoil online as my local dealer keeps some product in stock and he also lets everyone know when he is making one of his trip to the warehouse {he goes 2-3 times a year} thus I avoid paying shipping cost by buying ahead of time.

 

Anyone have experience with Valvoline 75W-90 high performance gear oil .

I like there products for my Oil changes and transmission fluid. Thought I would stick with them for my differential as well.

Just have a rear diff. with my 2wd,, only need about 5 quarts?

Thoughts?

Strea

 

Strea,

I use Valvoline Synthetic. Not the "high performance gear oil" but the normal synthetic in the goldish jugs. I usually try to stick with Vavloline products. I have had goo luck with it. I use thier ATF, Brake Fluid, Gear Oil, and Grease.