If you look at the MSDS for almost every injector cleaner, Naphtha is listed as the main ingredient. Naphtha is waaaaaay cheaper in a more common Walmart form as Coleman fuel. Last time I changed my filter I "flushed" my system by draining the bowl and filling it half way with coleman fuel. Pretty simple and really close to the Seafoam instructions. Filling it half way leaves room for the filter to drop in without spilling. I think it made a difference of 1 MPG. But in all reality, it probably was more of a feel good thing. That couple of ounces in the filter bowl surely ran through too fast to make any real difference. But it was still cheaper than "injector" cleaner.

The best fuel system flush is a tank of biodiesel. The local MFA used to sell 5%. Mileage goes down about 1 MPG, but it will blacken a fuel filter in one tank full. I did a lot of reading and there is a high solvent factor with bio. Plus you get the benefit of the added lubricity that ULSD is lacking. I put a new filter in to see what it would look like with bio run through it. After one tank, it was black. So I ran another tank through, then changed the filter and switched to regular diesel.

If someone would carry it around here again, I would run that all the time. It was a couple cents more than regular, but it was cheaper than using a cleaner. 30 miles less plus 5 cents per gallon equals about 4 dollars per tank.