Hi Mike,
Yes, this is exactly why I keep the engine idling in situations where I am in the middle of traffic; one does not want to taunt Murphy's Law, after all! So, my question remains: what idle speed should I use for these situations? I'm thinking I will set it for 1200 rpm as a high idle, just to be on the safe side. (I don't want carbon build-up or slobber.) Anyone have an idea how quickly the carbon build-up problem occurs? Does this only happen after years of bad-idle practice, or does engine damage happen in the first trip or two that one has let the engine idle for 20 minutes or more a few times? (Seems like if it was this immediate a threat to engine health, there would be more prominent warnings in the owner's manuals, et cetera.) Maybe Dave Atherton has an opinion or suggestion?