5ltretr, my RC fans come on at 173, I watch the temp gauge go down, then they go off at 162. Thus, the normal operating temp varies up and down between 162 and 173.
Those RC fans are cheap, easy to install, and highly effective for putting your mind and motor at ease while driving. If you get one, I recommend you inspect the wire/pin connections in the adaptor and ground each of the black wires.