I have used Royal Purple on both of the trucks I have been running.

Both of the trucks had over 500,000 miles on them.

In fact, I do not pay full price for the fluid, but I have no problem with the quality.

It comes down to how much you think your truck is worth and the value of the product you use.

 

Royal Purple all the way. I run it in all my gear boxes. Work and play.[redface]

 

Does oil wear out? Or does it just get dirty and contaminated? If the oil in a diff is clean does it need to be replaced just because of miles? Pre-packed u joints and bearings can go 150,000 miles with the same grease but a diff needs new oil at 15K or so? Unlike an engine, a diff has no products of combustion to deal with, so other that gear wear how does it get dirty? and if the gears are wearing that much in 15K miles you are going to have other problems.

 

Yes, as a matter of fact I DID look at the link you provided. I have seen that link before, and read that information. You will notice is is referenced to 2004 year model trucks. Since that TSB, there has been other information released in the form of service bulletins that is more up to date. I made reference to the Carson Dodge website/forums, that is where you will find that same information you posted AND a lot more information.



CD

 

Yes there are differences, but they are the same axle design with the exact same rated capacity just with different build specs for Dodge and GM. Everything on the the Dodge version is stronger. Stronger axles, larger tubes, better bearings. The point I am putting out is that Dodge's recommended gear oil change interval is grossly premature. GM says if you run a true synthetic then there is no need for a scheduled change interval.

It's more than a few dollars and you are still using an inferior gear oil. As long as the gear oil going in has the GL-5 spec, then it is fine for use. Mopar gets approx $30-$35 a quart. That is highway robbery to the extreme and is a mediocre gear oil at best. You can get a true group IV synthetic for 1/3rd the cost and get 3x the life out of it with ZERO adverse effects.

 

By all means point us in the right direction then. There are three TSB's for our Ram axles discussing fill level and oil weights and each one superceding the previous. The TSB's are 03-001-04, 03-001-04 Rev A. and 03-003-06.

 

Im an Amsoil dealer, so I am a bit biased, but I run Severe Gear 75w90 in my diffs, and run empty with this truck 99.9% of the time. According to Amsoil, their drain interval is 100,000 miles. I've trusted them long enough to know that it works. I've got about 30k on my diffs fluid right now...
Scott

 

I run Lubrication Engineers Monolec 703 80W90.

 

Mine feel a little rough at 20K miles so that is when I change them.


I've used Royal Purple, Valvoline, and Mobil 1 so far. Have 72K miles on the truck.

 

Where is the information about grossly premature? I've seen and heard from drivetrain specialists that 15k is a good number, period. A can't-screw-it-up-number.

And don't put words in my mouth, I haven't advocated for any particular brand of oil. I simply would not EVER substitute dino for synthetic when called for. Going by the book is pretty well foolproof. For what it's worth I've been using synthetic for nearly 30-years, have used oil analysis for real numbers, and have yet to hear of a decently-maintained AAM failing prematurely

Don't get me wrong, NavyDood, I like all the stuff you posted (wherever found). But I've also learned that it's easy to believe in the superiority of a "better" formulated oil . . and failed to back that up with multiple analyses. Once is not enough. The Dodge stuff may be expensive. And not the best. So what, compared to the cost of a rear axle setup?

The OP asked if it's OK to sub a cheap, non-spec oil. Have we covered that now? Because if an owner just goes by the book the worst that will happen is that he pays a bit more. Compared to the cost of the truck and the number of times the axle fluid is changed it's still not expensive over the life of the truck.

Better than spec oil is a different question from the OP, as is the cost of labor to change it. The difference between fluids is not so easily determined as different labs and different techs can come to conclusions that may not actually reveal anything.

If one can afford Terry (or his peers), then one is on the right track. If one is not willing, then stay with factory spec oil and factory change schedule. As with "towing heavy" and the rest, one is sailing into uncharted waters without a TSB or other guideline from the factory

 

I understand what you are saying too. Don't know how you came up with me putting words in your mouth though. Your research comes from the same place as most everyone elses in this infant world we live in now. The Internet. Everything is readily available and spood fed to us through this great/not great electronic encyclopedia.

Just because the manual or dealer says what it should be does not mean it is gospel. Well, for warranty purposes I guess it does. Real world usage and results will always hold way more credibilty in my world than Dodge Engineers and the dealer. So on that note, I guess I better start saving for a new rear end since I have almost 100,000 miles on the same gear oil.

 

Contamination! If it's clean why change it right?

Ford says as long as their factory fluid (synthetic) stays clean there is no need to change it. And by clean they mean no water contamination. This applies to the ford axles and the danas they use in the super duties.

 

maybe its just AAM axles, my mitsubishi went 350k with the factory fluid....LOL

 

Isn't there a clutch additive that wears out in GL5?

I don't know how these diffs work though, clutch or not.

 

Many of your gear oils come with a friction modifier already in it. The 11.5 aam in the Dodge has no clutches in the diff, and the 11.5 aam in GM trucks has clutch looking plates, but there is no friction material on them. Neither require a friction modifier. Ford is the only one that requires any.

I have heard of problems out of the ford units chattering around turns, but fords fix is to throw another bottle of friction modifier in there if it is under warranty. I would service mine at that time though if that ever happened.