1 gallon of toluene, 4 OZ's MMO per full tank of gas. The degrading of rubber is not a HUGE problem unless it spends a whole lot of time in the lines. I used it in LPHV pumps to clean the lines and the machine has had the same hoses for 8 years with constant use of toluene. It does make a HUGE difference and since I don't have cats anymore that's not a concern for me.