Here is a direct quote from Traxxas. It comes from the link I posted above.

"After the engine is running, it is important to keep the temperature of the engine up around 200 to 215 degrees during break-in. In weather below 45 degrees, the TRX2.5 engine will not want to run over 160 to 180 degrees (when tuned at proper break-n mixture settings). This is too cool for break-in. Do not lean the engine to get a hotter temperature. This will decrease lubrication as well, and will also cause your piston/sleeve to wear prematurely.

You all can make up your own minds. Believe the engineers that designed and built the motor or some guy that "says" he "builds" cars. It's your choice. I'm done.