AMSOIL

wolverine · Aug 23, 2025

Everywhere I've read, Mobil makes AcDelco's DexosD 0w20 for the LM2/LZ0 Duramax. They've also been a longtime supplier of the 0w20 Dexos1 for the gas engines. Oil analysis between the Mobil1 and AcDelco oils supplied by Mobil stack up very similarly.

I can't get behind the extra cost and paying more middlemen and distributors for Amsoil when I don't intend to extend my drain intervals, and when Mobil (and other brands) are already so good. Amsoil may use a better base stock, but IMO it's just not needed to take care of these engines which will last hundreds of thousands of miles on good oils from Mobil and others.

irk_miller · Aug 23, 2025

RET-G said:
GM's oil is NOT made by GM; good possibility it is made by Mobil since GM has had a long relationship with Mobil. However, I cannot say for sure who makes GM's Dexos D oil; however, Mobil was one of the first to have it out of the gate.
I'll continue to use Mobil 1 and someday get an oil sample and send off. One thing people should not forget is fuel migration into the oil. Mobil or Amsoil fuel degrades the oil.

Dexos is a standard developed by GM for GM vehicles. It's not specific to a brand. There are quite a few dexos licensed oils on the market. AC Delco branded dexos certified oils are made by several different manufacturers, including ExxonMobile, Chevron and others.

Stormin08 · Aug 23, 2025

lots of "others" have to pay for oils that meet DEXOS, that dont need it.

is or was GM onto something, or is it marketing and money on their part...i have read, that the DEXOS spec is superior performing for Direct Inject and Small Cu. In. turbo motors.

RET-G · Aug 23, 2025

Ok...two different statements about who makes the 0w20 oil, used at the factory and the dealership. And true, dexos is not specific to any oil brand, but not sure that was being discussed. I was wondering if Mobil made the oil for GM. Maybe a call to an unclassified, salary engineer I know at GM in Rochester HIlls MI, who happens to be in the trans area but I'm sure he can get the answer.