Diff fluid OCI in 2018 Chevy 2500HD Duramax

[oliver88]

So I have a new Chevy 2500 HD with the 11.5" AAM axle in the rear.....As I was looking through ther maintenance section of the Owners Manual I was surprised to see that Chevy does not recommend regular differential fluid service. Is this a "lifetime fill" ? We also have a 3500 Ram cummins and it is the same axle...They recommend 15,000 miles for the OCI....In the past I have changed out the factory fill at around 5000 miles and replaced it with 75w110 Amsoil Severe Gear followed by changes at 75-100K intervals. Curios as to why Chevy and Ram have totally different recommendations and also curious to what the Board thinks...Change it out or run it for the "lifetime fill" as per Chevy ?

 

[oliver88]

PS...We tow 18-22,000 pounds with the Ram and 8-10,000 pounds with the Chevy.

 

[Snagglefoot]

Seems that GM has been going that way but the feedback I’ve been getting on transmissions and diffs is this: Since the manufacturers know most buyers sell their vehicles before 150,000 miles, and only 5 % of trucks are on the road past 200,000 miles it’s up to the Bitogers to come up with a system. I think your system probably works. Let the diff get broken in and wear off the original machined edges. You suggested 5,000 miles and perhaps others have variations on that mileage. Then pick an interval to change it at. Your suggestion is 75,000 to 100,000. Others might pick shorter ones that range from 30,000 to every Friday. I use 50,000 miles and that same diff has 150,000 miles under my 2008 3/4 ton and works well. Let’s hear the other ideas.

 

[PiperOne]

Our Duramax's get an initial diff fluid change at around 20,000 miles. They get re filled with Chevron Delo 75w90 synthetic oil and we don't change it again unless we have to open up the diff for something (leaky cover, pinion seal etc). Several high milers and no issues ever. We do not add any limited slip or any other additives. I would also not run a diff oil that is 110 (thick isn't "better") and would be worried about an oil with that kind of viscosity spread holding up over a longer service interval. Towing the weights you stated is a looooong way off of anything I would call severe duty...even if you towed that daily. It's a very good axle..just keep it full.

 

[clinebarger]

Every 50,000 is good when using a good synthetic gear oil, My 11.5" differential has 380,000 miles on it with 75w90 using this schedule.

The Dodge severe service table is pretty ridiculous.

 

[CarbonSteel]

Originally Posted By: PiperOne
I would also not run a diff oil that is 110 (thick isn't "better") and would be worried about an oil with that kind of viscosity spread holding up over a longer service interval.
75W-110 is the upper viscosity that 75W-90 used to be before the J306 tables were updated so it is not "thick" and Amsoil Severe Gear will definitely last through a very long interval--typically 100K or more.

OP - I would run it without a second thought.

 

[PiperOne]

OK....But that 75-90 (Delo and many other brands) will provide all the protection the axle needs...without the extra drag...and it's stable enough to be left in a semi truck for 750,000 miles. The difference between the 110 and the 90 I use is 5 Cst at 100C...that's a fair bit. To each their own I guess.

 

[Black_Thunder]

75w110 is considered thick?


Ford has been factory filling trucks and suvs with 75w140 rear axles from factory since the 90's