Feets helped me through my over heating problem on my 1969 RR. The IR temp gun makes a night or day difference and have since used it on other things. WELL WORTH IT!!!! Mine was a radiator but ran hot even with no stat. but I took all the readings at different times on different days and checked each cyl. temp just to make sure. There is also a test kit to check for combustion gas in your cooling system, also a great thing to have around.