Nitormethane and oil wont degrade plastic or rubber unless it is left there for a LONG time. I never use after run oil or bother to clean out my tank and my os .18 is on 6 gallons and my cen .16 got 10 before she died. Only time I do anything is if im leaving it sit for 2 or more weeks. then I will empty the tank and throw some WD40 in the combustion chamber.