I have been using it for two years with intensive, long hours of use at high speeds. The cylinder pistons in the machines (both branded and Chinese) are in perfect condition. They are polished, without any damage or carbon deposits, even though I use a little more oil than necessary. It does not smoke, even if I add a considerable amount. Sometimes it may have a very slight smell in the exhaust gases, but it is not bothersome. The price for what it offers is excellent. I highly recommend it.