I'd like to add an image to the pinging or "Pinking" topic.
This is what happens when you do one of two things (pic)
1.) Your plug heat range is too hot for high speed driving.
2.) You filled up with rot gut petrol and hit the Autobahn.
Now if you are Grandpa and putter around the flatlands rot gut is 'ok'.
But if you climb hills and enjoy power, then rot gut will eventually
duplicate your engine to the pic.