Could you explain this a bit more, how using a "cooler" plug helps with fouling plugs? What else is affected by this heat rating or more accurately what symptoms help someone know if we should move up or down in the rating? Much appreciated!
You misunderstood me.
I made some corrections above.
I AM NO EXPERT, by far, but what I had been told by different people in parts stores (way back) that a 7 is a normal all around (city and mostly highway plug), an 8 is hotter and for stop and go traffic.
9 I was told is too hot, too strong a spark (?)
I guess to answer your question:
the way I was told and explained :
a hotter plug is like running the car too lean of a mixture. It creates too much heat in the combustion chamber and you're risking a burnt valve (exhaust usually) or worse, the top of your piston melting.
Won't swear to it, but I don't think so. I believe 220SE uses W7DC.
sounds about right, I think the W7DC
stands for copper (the good old Bosch opper or Plus plug before they started those stupid platinum things).