I bought 2 cases of the Shell DFA when it first came on the market. I used it in my PSD Ford. The engine seemed more noisey with this additive. It is touted as a good cleaner and to prevent gelling. It will do the job for you. But for a top cleaner and lube I think FP from Otis Bever would do a better job and alot cheaper. The FP is used at a rate of 1oz to 5 gallons of fuel.