One of the local dealerships is offering a Cummins synthetic oil and filter change for something like $169.

While I run Mobil 1 on my 172,000 mile Hemi, I wonder about it in a Cummins.

I thought one of the major reasons to change the oil was to remove the soot, so I wonder if extending the mileage between changes was a good idea.

I have always heard that were was a Valvoline/Cummins branded oil that was good but I have never seen it for sale. However I have not looked very hard.