Which models are you using? How long are they lasting? I would like to hear from you guys that actually run them more than about an hour a day. We do a super job maintaning all our equipment and use synthetic 2 stroke oil. And still usually only get a year out of an Echo 260. We may have these machines run 4-5 hours a day. Just tried a Shindawia. 8 months life, took it back under warrentee. Dealer said it was "OVERHEATED", voided warrenttee, and wants to charge to look at it.