Well, I'm actually in NorCal now. My location info is old....

Btw, I don't have any pre-ignition issues. I'm just asking out of curiosity.

I've always used Chevr@n 91, but one of my cats had been plugged up (replaced in about a week), and it's probably caused some valve clacking. (All oil plugs are good.) For the top engine clean, I've used MMO through the brake booster, through the PCV, and water through the same two hoses. I'm now also pouring in MMO directly into the plug wells, with the piston just after TDC and the intake valve slightly open. Pouring the MMO that way, I can actually soak the intake valves. Plus, if there is any carbon on the exhaust valve, that should leak MMO slightly and soak.

All this activity has changed the spark plug appearance. The MMO actually didn't cause much change, but the water created a lean condition, so the plugs are a bit blistered.

Anyway, that's just all info for fun. My question is, do old engines benefit from colder spark plugs due to increased compressions ratios....

__________________
Beware of stealers
(and shill posters who work for stealers)