toyfan2 Report post Posted March 22, 2021 106k on my FFH and decided to change plugs. i used SF530 Motorcrap plugs and found this. Cylinder 3 plug had a ton of oil on the threads so i boroscoped that cylinder and found a rather clean piston. I know that the engine itself doesn't actually have that but am i to be alarmed? Granted i didn't check the other holes as i was just worried about the oil on the plug. i look at the electrode as well and it is of a different color than the other plugs. as seen in the attached photos. I'm not seeing any real world issues on this engine in my basic searches. i was really expecting a bit more carbon build up Quote Share this post Link to post Share on other sites
lolder Report post Posted March 23, 2021 (edited) The engines run very clean and lean so no carbon is normal. The Atkinson cycle has the engine run at almost wide open throttle whenever it runs so no idling. It always runs above 1000-1100 rpm. Was that the only plug that was discolored? How did the electrode of the new plug compare. I believe they are platinum plugs. I decided I was never going to replace a plug unless it missed. Edited March 23, 2021 by lolder Quote Share this post Link to post Share on other sites
toyfan2 Report post Posted March 23, 2021 the other plugs look normal worn with a bit of carbon soot as seen in the side by side pic. the #3 appeared more beige. Quote Share this post Link to post Share on other sites
MeeLee Report post Posted March 27, 2021 Could it be from spilling oil during an oil change? Quote Share this post Link to post Share on other sites
