Can I use the 75W-140 gear lube from AMSOIL or do I have to use the 90 weight stuff,I have the 140 left over from my Dana 80 and hate not using it.Any info would be great.

By the way,dealer says it is OK to use the 140,but I want to be safe than sorry..Thanks

 

A call to AAM will reveal that they RECOMMEND the 140,..not the 90. Also they RECOMMEND the synthetic w/ NO additives, fyi. Specifically they RECOMMEND the DCX synthetic since they know what's in it, and have tested it extensively and they don't know what's in the other brand synthetics. Some have abrasives that can mess with your seals and over time your bearings etc. AAM told me they have tested the 140 at maximumu heavy loads and the 140 is the MAN and they don't recommend the 90 even if it was a synthetic. And yes,... the DCX will cost more. But looks pretty cheap if you have a problem with something else. Hope that helps.

 

A call to AAM will reveal that they RECOMMEND the 140,..not the 90. Also they RECOMMEND the synthetic w/ NO additives, fyi. Specifically they RECOMMEND the DCX synthetic since they know what's in it, and have tested it extensively and they don't know what's in the other brand synthetics. Some have abrasives that can mess with your seals and over time your bearings etc. AAM told me they have tested the 140 at maximumu heavy loads and the 140 is the MAN and they don't recommend the 90 even if it was a synthetic. And yes,... the DCX will cost more. But looks pretty cheap if you have a problem with something else. Hope that helps.

 

There was a link about this a while back. I posted that the guy at my dealership said that they now recommend 75w-140 for people who tow, even though the book says 75W-90. Either must be full synthetic.

Anyhow, they sold me some Redline 75W-140, saying it would not void warranty and the heavier weight gives a little more margin of protection....

 

Has anyone been able to find a link to AAM re the product specs for lube oil? I could not.

 

Ok, this is getting confusing. AAM is shipping the rearends to Dodge with 75w-90. But they recommend 75w-140.
Pretty soon I will be needing to service the rearend and install a PML aluminum diff cover for extra capacity.

MikeyB

 

A month or two back I called AAM since I was putting a Mag Tech on and wanted to be double dangded sure I had the right stuff. They told me at that time that they had been a bit at odds with DCX on the fluid requirements and that they recommended the 75w-140 synthetic that is available from you DCX dealer and only that. They were aware that it was different from what OEM provided with the new trucks and the guy I talk to said they (AAM) had done extensive testing and their recommendation was the 75W-140 synthetic. I believe his name was Bob Dunn. I spent the extra $ for the good stuff and that's what's in my truck as I feel the manufacturer of that part must know what's best for their product as they will have to stand behind it for warranty. Hope that helps and removes some of the fog that there appeared to be confusion on what was best for our trucks. No confusion IMO.

 

Thanks. I will go with the 75w-140. Either Mopar or Redline.

MikeyB

 

Does anyone have a buddy with a new Chevy with the with the same axle? That might help alleviate some of the confusion, or add to it depending on what their literature calls for.

 

Friends don't let friends drive Chebbies!

Sorry, couldn't resist!

I went with 75w140 in the 80 I had under my 1999. When it comes time, I will go with the same in the 11.5 under this one.

2 reasons - first I feel that AAM is in a lot better position to judge what is best for their product, and second I have never heard of anyone who has been given grief over the fluids they used in the differentials (as long as ya ain't runnin ATF or something silly like that).

Curious on this actually if anyone has any thoughts. I could be wrong as rain here, but really....can anyone honestly look at used 90 versus 140 and tell the difference? Outside of a pour test or something like that? Thinking of the guy at the dealer who'd be doing the work if there was an issue. Much less brand X versus brand Y.

Matt

 

The reason I want the specs including viscosity is that all oil is not created equal. Some diff GL5 oil has ingredients that can damage seals. Just saying 75W-90 or 140 is not good enough.

Also what about viscosity for engine oil if winter sets in and you are not broke in. Strike that I will pose another thread.

 

Yeah I want to use Amsoil exclusively if possible.

 

I put in the AMSOIL 140 at 17K, I now have 20K and a big tow under my belt. I had no problems, 110+* 50-70 MPH depending on grade.

Tom

Not sure how the toe got under my belt but it was there...