Bet you added the "wrong oil" to your LM2

[exp500]

Remember the DC-9 that Lawn Darted in the Florida Swamp? That was listed as a "mixed" grease mishap. Several varieties used, all certified, but incompatible. At the time, a tube of Mobil 28 was $38.00 and is still the only approved for that Jackscrew location.

 

[stallion_412]

Amsoil 0w20 meets or exceeds the requirements for Dexos D: https://www.amsoil.com/p/synthetic-diesel-oil-sae-0w-20-dp0/ click the data bulletin and scroll down to 'Applications'
Per your owner's manual, "Use engine oils that meet the dexosD specification." That doesn't mean they have to be certified, just have to meet the spec.
As far as warranty, also in your owner's manual: "Failure to use the recommended engine oil or equivalent can result in engine damage not covered by the vehicle warranty."

Amsoil (among non-certified other oils) would that 'equivalent'

 

[EGTroup]

Amsoil 0-20 Diesel is DexosD certified per the attached spec sheet on 2nd page.

 

[Stbentoak]

This bulletin is over 2 years old and proves nothing. Until it shows up on the official GM approved list….it’s “unapproved “….

 

[OBSSSD]

I just used the GM oil that the Duramax store sells the change kit online, with the filter and 7 qts