What is the best lube to add to the fuel of a 2005 Dodge cummings

No..dont need to.

IF u can get Biodiesel, use it in a blend. 20% is a very commonly availabe blend. You may need a fuel filter change right after u start using is, as biodiesel will clean out the gunk in ur tank. Then it will keep ur injectors VERY clean!. Cummins diesels like it. I live in very Hippy-dippy Oregon, so there r a lot of bio-nuts out here running their trucks on Bio.

Biodiesel is a fuel that can be used directly in any diesel engine generally without modification. It is viscosity is twice that of regular diesel fuel which means it is better at lubricating ur diesel engine than regular diesel. And. emissions r cut dramatically vs using standard diesel fuel.

Waste oil conversions r a different story & r not healthy for long term use, dont confuse it with Biodiesel.

If u cant find it, its easy to make too.more reading here
http://journeytoforever.org/biodiesel.html

Schaler Resilone. I am not at all sure of the spelling but any good auto parts store will have it in stock (Pep Boys or Kragen). This product is widely known and accepted by deisel mechanics. Your cummings engine is a six cylinder deisel engine - one of the best. Use this product with each oil change in place of one quart of oil. Do not ask Dodge anything about your engine. They are auto manufacturers not engine manufacturers. Check with Cummings always.

use it it will help and if the dealer wants to be a know it all call and ask him and see if he knows