I use Power Service [ diesel fuel supplement w/cetane boost ] in all my diesel tractors and Cummins diesel truck. I put about 1/2" in the bottom of a 2" diameter can and dump that into the empty 5 gallon can. [nothing scientific here, just what I do] Do not use it all the time, just usually for fuel I procure for the winter. Or for a tractor that will be stored over winter. The supplement is not as important as making sure keep your tank as full as possible, you buy fresh diesel from well used diesel pumps, and stay away from seldom used gas stations that sell diesel only occasionally. ' Usually ', a well used pump is that way because folks prove daily that it's good fuel at a reasonable price. They also stay far away from bad stations. The supplement will not fix bad fuel, it only adds a little to the lubricity/lower gel temp/cetane/etc. to the base fuel. And make you sleep a little better at night if you use it some. Fresh diesel has a little more snap in it, something you can sense if you drive enough. [ or is it imagine ]