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 ?
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