fuel additives

[kip Foss]

What is the general concensis on the usefullness of fuel additives? I have two Diesel trucks and asked my fuel injection man about additives. He says that for Diesels additives are mostly a waste of time and money. He says that there are enough additives in fuel to do what additives claim they do.

My Mercedes mechanic says that for gasoline cars with fuel injectors that some additives are worth the effort. He recommended one made by, I believe he said, BG.

Does anyone have any experience with gas fuel additives?

I think there are a few threads already with a great deal of information on this topic. On high mileage cars they have proven extremely useful to me, not sure of how much benefit they will be on newer engines.

I have experience with both, for diesel I would recommend the Shell Rotella DFA, add about one-fifth the recommended amount, since the recommendation is based on 100 gallons and a Mercedes tank holds about 20 gallons. In the summer, I only add every few tanks, when the weather gets cold, every tank. The instructions say to add to a nearly empty tank, not certain why that is but I always do it that way.

For gasolene engines, I can tell you the synthetic cleaners have made a major difference in keeping my jag fuel injectors clear. I use the Valvolene or Chevron/Techron products, again these are added to a nearly empty tank. I am less certain about the benefit to the Cadillac, although it appeared MPG did improve following the cleaning. I add this a couple of times per year. Then every month or two, I add fuel injector cleaner to the jag, it seems to help starting the engine. I have never added FI cleaner to the Cadillac as there does not seem to be a need.

My opinion is these cleaners will make a noticeable difference in the performance at least of older engines. I document the 300SD fuel economy carefully and it is consistently better after I add the DFA than just before. I doubt they will solve actual mechanical problems, but keeping the engine clean may prevent such.