I've used so many other various fuel system cleaners, including Redline SI-1 to clean out my Corolla, especially the combustion chambers. When I used it before, I split the bottle in half between two tanks since it only has a 10 gallon tank. This time I put the whole bottle in. Two tankfuls after the full on Redline cleaning, my car runs better than it ever has. Peppier, ping is almost totally gone, starts easier in the subzero mornings, idles smoother. Don't buy anything else IMO!