[Roger V]

Understand in some company's test that water runs thirty degrees cooler than 50-50. I use (distilled) with Prestone or Peak rust inhibitor (has water pump lube). Like already mentioned a four blade isn't needed if all else is good. Supposedly, it causes more drag on the engine needlessly using up some horsepower. In your case it would add to the heat build-up. Agree that you don't even need a fan beyond low speeds. Usually, the radiator is the cause for overheating so rechecking is good advice. Since your engine isn't broken in yet, running 55-60 likely would be hard on it and add to the running temperature.