Just purchased a 28 Grady Release with twin 225 Yamaha 4 strokes with 425 hours. All maintenance records look complete by certified Yamaha mechanic over the life of the engines with the exception of thermostat replacement. I read the manual and did not see any recomended maintenance schedule for thermostats. I've always had them changed every year on all my two strokes. Any input on scheduled thermostat maintenance would be appreciated.
