I just replaced mine after almost 2 gallons plus the break in ( maybe 2.5-2 3/4 gallons total)... I had a ghost flame after a pit stop and couldn't find anything else wrong so thru a plug at it. Looking at the old plug, it was a touch shinney brownish black from carbon build up/ oil burning on the inside of the cone and just at a touch grey on the coil but not distorted at all. Engine was running great before and continued to run great after the plug change.