The outboard manufacturers use a lower temp t-stat than automotive because outboards often run in salt water. Hotter running engines will accumulate salt build up faster than those running a bit cooler. So you have to choose...check and change the oil more often or pull the heads and clean out the water passages to prevent hot spots and corrosion. I'd rather change the oil a few more times. Which is what I do with my kicker...when the hours aren't that many and the oil is not too dirty I will just drop the oil and get another round out of the filter.