I have two quetions with the same topic.
1. Has anyone put both types of fuel the new and improved ULSD and the old stuff together in the same tank? What did you see or feel going on?
2. ULSD buy itself, is it good or stick to the old stuff for as long as i can?

Aslo at what point of a brand new truck (4200 miles) should you put in diesel fuel additives.

 

If you can still get the LSD use it. Mixing ULSD & LSD will not make any difference that I know of. I do not put any additives in my truck. Some put it in every fill. My dealership tells me " if Cummins and Dodge thought you need it they would tell you to add it". I think it is more important to get fuel at a good place that is used frequently, so your truck does not get some old stuff. I go to a Mobil that is by the tollway. Truck ran fine thru winter, 26k so far.

 

Yes, If you can get the LSD use it. I use an additive every other or every 3rd fill up just for my own piece of mind. The power service does seem to help a bit with mileage also.

 

Well I am sure at some point there was a mix. Diesel pump labels here in Houston do not seem to be up to date if any. I buy most of my diesel from local neighborhood Wally-World grocery. Been buying there for three years now with no disasterous issues. For a little extra insurance I use mix of PS/MMO in EVERY tank.

 

There is still some LSD in East Texas. At first I thought the pump tags hadn't been changed, but as of last weekend, its definitely LSD, not ULSD. In my company truck,D-Max, you could hear a more pronounced injector noise with ULSD and no additive. But the Cummins doesn't seem to change... Or that could be my selective hearing loss from being married!!!!.. The D-max does quiten down on ULSD with Cat fuel conditioner.