KC,

180 degrees is actually a good temperature for the engine. The problem is only that at that temperature, with raw water cooling, there will be more salt deposited in the cooling passages. If you are going to clean out the cooling system in a couple of months anyway, why worry. Other than having a little more salt for the acid to remove, it won't hurt the engine. I think you are more likely to cause a problem running as low as 120 degrees due to condensation.