When I was building engines, I would cut the plugs apart to see how they were doing. Just slice off the crimp ring around the top and carefully pull the insulator out to get the plug to reveal all the secrets hiding under the metal shell. The one thing you never want to see is aluminum "whiskers" on the porcelain. It means the tops of the pistons are eroding and very bad things will be happening shortly.

 

If you ar spraying over 150 shot some sord of high octane fuel need to be used ,like 100 octane unleaded mixed w 93 so you dont get pre ignition or detonation and yes two step colder plugs,

 

Just an update. Lexus checked cylinder #8 and found nothing wrong what so ever with the plug or the coil. They took the plug and moved it to #4 and took the coil and moved it to #2. We will see if there are any new problems that come up. I drove her pretty hard coming home and she felt very sharp, very strong!

 

Cool beans ! One step colder plugs and some 100oct mix w 93 , when spraying!