I have a high mileage 5.9 cummins with some extra go go parts and with the oil additive it runs a little smoother and cleaner. Fuel additive also helped with my mpg.
Great products and will for ever use.
My 6.0 fires tight up no sluggish start and runs like a new truck!!!
Have been using in 2004 ,6.0 for many years, great mileage no stiction. quieter running. Never without.