[WardL]

Karl, your rule works at 0 C because 0 C actually is 32 F. I don't worry about converting the C to F all the time, but then I don't understand my water temps. I've got an 85 C (185 F) thermostat. I would expect the water temperature to warm up to 85 C and then drift up and down as the cooling load changes. Seems like once warmed up, the temp should not go any lower than 85 C. I don't understand when it is 60 F or cooler, the temp gauge barely gets above 50 C. I use cardboard to partially block the radiator, but that only raises it to 60 C. I'm pretty sure the temp gauge works because it can get up to 90-ish when no air is getting pushed through the radiator.