I bought the car 3 years ago, used with 13,000 miles on it. I had the system flushed at about 30,000 miles ago. As for the thermostat? No idea. I’d guess it is the original. Very disappointed in this car. Power steering pump blew at 55K, fuses blow instantly if I try to plug in a portable air compressor, the engine gets hot while going up steep hills, the Check Engine light comes and goes periodically and now the erratic temp gauge. The car has 67k on it. I also own a 93’ Chevy work truck with nearly 300k and the thing never gave me a problem. Thank you, I will take your advice to the dealer along with my overheating car next month when I am back Stateside. Have a great day. CM