The company I work for has 8 or 9 cummins p/u's they use fleetguard. It also says right on the side of the filter "cummins oem approved" you can't go wrong with a fleetguard.

 

I hope it says that being that fleetgaurd is a wholly owned subsidary of cummins engine company and by the way NAPA filters are made by Wix and are a very high quality filter and I have used both currently there is a NAPA filter on it.

 

The fact remains that if you happen to have an engine failure with any filter other than an "approved" filter (which Wix or NAPA is not) - you will very likely NOT be covered by any warranty. The oil and oil filter is usually the first thing they will look at.

 

Why risk it over a couple of pennies. Use approved filters and have no worries.
I have done 4 oil changes to date, I walk into the Cummins shop, they already recognize me(I'm hard to forget), ask me if I'm doing an oil change and go get me the filter. Sure beats the dealership. I am not willing to risk any problems over a filter and if Fleetgaurd causes a problem, I feel DC will take care of it.

Just my .02 worth.