I plan on switching to Delvac 1 once I hit the 10K mark. For the first 2 changes (1K and 5K), I was going to stick to dino to allow proper break-in. For gas engines my first choice is Castrol. Any recommendations for the Duramax?


Also, it appears from the threads that you can use Mobil 1 gear oil in the front axle without bringing the warranty into question. Is that true?


Thanks

Mobil Delvac 1300 15w-40, but others may suggest Delo or Rotella.


Any WalMart probably has all three.

Since oil is really cheap I will change it often. It makes not much difference which brand to use as long the required API specs are fulfilled - thats only my opinion of course! I had not such a good experience with synthetics on a new engine so far. Normal mineral oil is good enough if changed often enough.