Jinma 454 with C490bt, Thermostat cross reference

Yes yes, warmer is better. I can only conclude that the reason some of these Chinese tractors operate at 60° – 71° C is that is gives more wiggle room for overheating. But given that they don’t incorporate a coolant recovery system indicates they are reluctant to change to modern day thinking.

Today’s engines operate at 82° – 93° C (180° – 200° F) for thermal efficiency. It allows for more complete combustion, resulting in less soot the oil carries in suspension which translates into less bearing wear, and a cleaner exhaust for less air pollution. It also lets the oil run at a higher temperature in order to “boil off” any moisture entrained in the oil.

If this looks like your thermostat it should be easy to cross reference, but you will have to take it into a parts store for comparison. The temperature values for this thermostat are unknown.

https://www.circlegtractorparts.com/cooling-system/490b-43002-thermostat

I recommend a thermostat rated 82° – 85° C. (180° – 185° F). You will notice a positive difference.