Of all the fuel additives I've used over the years, I've found Howe's Fuel Treatment offers the best of every thing (Power Service products are a single Florida ballot runner-up). It cleans the injectors & contains a lubricant to compensate for low sulfur fuel. Since using this product, exhaust smoke has been cut to unnoticeable in my MB's - once they've warmed-up. It's available at most truck stops for about $9 a bottle. If used as directed, a bottle treats 750 gallons! A bottle usually lasts me about 400 gallons ... over-use is not harmful. BTW, they have a "Power Cleaner" (also $9) that should be used for the initial treatment. I use it at each fuel filter change.
1980 240d 393K
1982 300sd 240K