I have a non DEF 12 2500 CTD and when not towing I'm just running here and there around town. Sometimes only 1-2 miles. I might make several 2-4 mile trips in one day. 15,000+ miles on it and no DPF issues. I only put about 10,000 miles a year on the truck, with 4000+ for towing. Pretty much from April till the 1st of Oct we are going somewhere camping/Rving and the rest of the time the truck just puts around town. At least once a week I will take the long way home to get the engine temp up to normal. Once every 5-6 weeks I may take a trip down the freeway to visit family 75 miles away. My understanding is that with the DEF your regens are less frequent or more passive. But with DEF it puts less particulates into the DPF. Or something like that. FWIW I run around town in 4th with the EB on. Not sure if it helps but it does keep the tranny from shifting up and down less.
Tough call I suppose. If I towed on the flats mostly the I would opted for the gasser. I tow a lot in the mountains so that's why I opted for the diesel. Just a more relaxed tow. On the freeway I run 62-65 and average 10.5-11.5. I've seen 11.9 towing from Redding Ca to Bend Or. That won't happen with a gasser. Only downside is that gas prices tend to be considerably cheaper more than not. This last summer it was nice in that diesel prices were actually less than reg gas. Now diesel has gone up and gas is dropping like crazy. If you're only driving 6 miles to work then fuel prices aren't really an issue.
If you're thinking of upgrading then the diesel will give you more options. Plus towing anything over 10,000lbs will be better with a diesel. Just me but I would want to tow 12-14,000lbs with any gasser.
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