I always break in my engines on the plane. Usually half a tank on the ground and then a couple in the air all running rich. Sometimes I get excited and just fly it on the first tank. I wouldn't recommend that for somebody that's new though. I have some engines that are 10+ years old and they still run fine. You just have to remember to get all the fuel out of them and keep them dry. These RC plane engines last a long time. I race the nitro powered RC cars and that's a different story. For each car, I'll go through three engines every summer. I can usually just replace the piston and sleeve, but that's $60 a pop. The engines cost around $150. REally sucks. Matt