Hi All;
I have a question about spark plug selection - specifically the heat range.
I'f I'm trying to burn off carbon a little better, do I go up or down in heat range?
i.e. The engine (Merc 4.1L L6) calls for AC Delco MR42TS, am I better or worse with AC Delco MR43TS (heat range of 3 vs 2)...