It will not blow from running at those temps. I don't understand why people have to run their engines at a specific temperature
Some of that will have to do with what fuel you are running. Fuels with a high content of synthetic oils will not provide as much protection at higher temps because the synthetic oils can actually break down and burn off, therefore providing little protection. Synthetic oils do, however, provide better protection at normal operating temps than castor oils since they don't leave behind the gummy goo. This is why most fuels have both.
If you believe that trying to keep an engine between 210 and 270 F is operating "at a specific temperature,' that's fine. I believe temp guns are for insurance, not as a device to tune by.
Any experienced engine guru will tell you to tune the engine by performance, not by temperature
Yes, and if they have the experience of the professional that modifies my engines, they will also tell you that temps over 300 can be unhealthy to any mill. They wont tell you it will cause it to blow, but they will tell you its going to shorten the lifespan.
This is my opinion, and it is what I have learned from people who professionally modify RC engines.