Thermostat recommendation.

IMHO.
1ST replace the thermostat what is called for by the manufacturer.

2nd as others have said if the engine runs hotter than the the thermostat you have a cooling issue. (Clogged radiator core, bad water pump, blocked water passages, pulley diameters not correct, fan not correct for the application, radiator not correct for the application, )

What engine, radiator, modifications, etc