Originally Posted by andrewwynn

The problem is the needle will not indicate a low temp problem. My car was running at 160 vs 190 degrees for 1000s of miles causing all sorts of problems (actual damage even). The needle reads "perfectly ok" over about a 40-50° F range and that is way too big of a range hence it really is a "shit is really broken" function; no clue that things may be slightly off. It's not a helpful gauge. It operates exactly like an idiot light. The dial shows some movement when engine is warming up, not a useful function. The fact the heat won't run until coolant is about 100°F is just as useful. The M54 engine at least will run rich until the coolant temp reaches something like 180F. 20+ higher than the gauge indicates good to go. If they were aligned than it would be great. They aren't so it sucks.