I'm not sure if anyone else is having this issue or not (and I'm guessing people are/should be). In one month, I have had an 036 Pro, 192T, and just cause a Mantis Tiller 50:1 all bite the big one and have scored bores. I noticed the engines were running rough, and would have to adjust the carb slightly. In the long run, something was causing the engine to run hot, and I was most likely doing is making the engine run leaner. The one thing between all 3 that I have switched is from HP Super to HP Ultra with 93 Octane gas. I know that Stihl only requires 89, however, the dealer told me when I switched that 93 is better in 2-cycles. When I questioned the dealer (and an e-mail to Stihl) they say that Ultra is the best, and should have no change other than cleaner running engines. One thing that the dealer has said was that ethanol content in gas will be increasing from 10 to 15% by Jan 1, 2012. He recommended using ethanol free gasoline from Shell to mix with the Ultra. However, a warning he also said is that any engine made prior to 2007, with a carburetor will have issues after Jan 1. Is anyone else in the same boat? I'm rebuilding the 036, and just bought a brand new 362 because parts for the 036 won't be in till the end of September.