American Axle 11.5"

[Slow Six]

The shop manual calls for the 75W-90 oil. I had some oil picked up today and they sent 75W-140 which the label on the jug says it is for all axles used for towing. Is this oil okay to use as I do tow a lot? I am using the Mopar oil.

 

[jray]

I'm running Amsoil 75-140 and have been for the past 80,000 miles. I also tow and that was the reason for choosing the heavier weight oil. I have had no issues with the heavy weight oil. I too have the AA 11. 5.

 

[amsoilman]

The heavier gear lube will run warmer. If you want to read about gear lubes, "Click" on the below link:

White Paper - A Study of Automotive Gear Lubes



Mopar did not do well in the tests, especially in the KRL 20 Hour "Shear Stability" test, where it went out of grade after the 20 hour testing. (PAGE 6)

 

[DGamelin]

I run 75-140 Castrol synthetics you wont find any thing better. I run from MI to TX where it is hot pulling goosenecks. I was having problems with the posi. An unusual amount of metal was in the lube. These AAM axles posi are prone to this because of how they work (helix gear). Thats why you are suppose to change the lube every 15k. At 55k the first posi was shot. It was replaced under warranty and started doing the same thing. I was running 75-90 synthetics of all kinds. When I switch to castrol 140 the filings on the magnet are very acceptable now. I read about a sheer test that was done on different gear lubes and the castrol out did them all by something like 16% thats why I tried it. It was hard to get in my area. I wouldnt worry about running 140. Your owner manual says you can for heavy loads.



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93 250 2wd xc 354 auto 271k

04. 5 3500 4wd qc dully 373 6speed 94k

 

[bheiting]

Don't ya think that 140 is a bit heavy for Canadian winters, eh?

 

[DGamelin]

I live in the upper peninsula of Michigan parallel with the Sault St Marie. If you are way north and dont hall a lot with the truck. I might go lighter. But a synthetic 140 is still a thin oil. And the first number 75w is your cold whether rating the second 140 is for how hard of work it is designed for. After the problems I had and what castrol did for me I would have a hard time going back. but we have trucks in here all the time using 80 or 90 not having any problems but they don't tow munch or often. I dont think 10k is munch of a load for these trucks. I tow 16 to 18k most of the time.



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93 250 2wd xc 354 auto 271k

04. 5 3500 4wd qc dully 373 6speed 94k