I had a TTR 28 engine that LOVED to run in the 300's range. Lasted me about 5.5 gallons (modded the sleeve at around gallon 3). They are right, as long as the engine isn't stuttering to run... its doing good on tune, no 2 engines will ever run at exactly the same temp either . I run sidewinder 20% race (10% oil) lasted my TTR 5.5 gallons of tuning nightmears [:'(]