Attention: TDR Forum Junkies 
ok i know this thread is for the 6. 7 but it got my attn and i have seen a few people reading this with a truck like mine. i sent cummins an email asking what oil to use. here is their answer.
Thank you for contacting Cummins. The resolution to your inquiry, oil recommendations, is as follows:
We would recommend an oil meeting CES 20081 since it superseeds and replaces all older classifications in a 15w40 weight for conventional, 5w40 for synthetic. Whether you use synthetic or conventional we recommend you stay with the same oil drain intervl outlined in your manual. Never base an oil drain interval on oil analysis since that will not tell the whole story such as depletion of the oil additive package put into the oil when it is refined, blended, and packaged. The only oil we will recommend by name is Valvoline Premium Blue or Valvoline Extreme Blue.
take from that what you want, i might still run the amsoil... .
Thank you for contacting Cummins. The resolution to your inquiry, oil recommendations, is as follows:
We would recommend an oil meeting CES 20081 since it superseeds and replaces all older classifications in a 15w40 weight for conventional, 5w40 for synthetic. Whether you use synthetic or conventional we recommend you stay with the same oil drain intervl outlined in your manual. Never base an oil drain interval on oil analysis since that will not tell the whole story such as depletion of the oil additive package put into the oil when it is refined, blended, and packaged. The only oil we will recommend by name is Valvoline Premium Blue or Valvoline Extreme Blue.
take from that what you want, i might still run the amsoil... .
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