my friend had a 1.5 with 287,000 miles on it after we put in sea foam in it and the smoke begain to clear it started to knock five days later it blew up but I also used it in my 97 civic the same day it only had 133,000 miles on it and it made a noticeable improvment in gas mileage and pick up so i would say it good stuff for cars in the 55,000 to 150,000 mile range but be careful on higher mileage engines