I'm not having much luck lately. Yesterday I took my older 4A for a drive. It overheated very strangely, right in the cool weather and after only 5 minutes of running. I checked the radiator. Coolant was low, and it's full of goopy, gritty muck at the filler neck. I pulled the dipstick. I'm "overfull" with the oil looking almost an orange opaque. What possibly has happened here, and could it relate to somewhat loud tappet noise I had been hearing over the past 8 months? Darn, I don't want to hear the diagnosis all that much. I've only got about 10K miles after a rebuild 10 years ago. Why would my head gasket fail? What a drag! OK, I'm listening . . . .