In the old days, 2 stroke oil, 30 weight motor oil, ATF, and Marvels were all used in diesel fuels with no ill affects, and maybe some good effects. With the new engines and diesel fuel, these old additives are now wifes tales and may well not be good for the modern electronic diesel engines. There are lots of old truckers around and these additives keep getting mentioned again and again, but as More Power sugggest, beware!
83 C10 Suburban, Silverado, 6.2, 700R4, 3.73, 31-10.50R15
82 C30 Crew Cab dually, 6.2, Banks, Th400, 4.10, Gear Vendors, 235-85R16
83 C20 Suburban, Sierra Classic, 6.2, 700R4, 4.10, custom paint, 285-50R20
95 Yukon, 6.5, 4L80E, 3.42, 265-50R20
73 GMC Astro 95, 8V71, 10 speed Roadranger, 110" WB, 6 each 11R24.5