Turkey greetings, My neighbor thought he would do me a favor while i was away at work so he jumped on my john deere riding tractor w/ kawasaki gasoline engine and mowed grass/mulched leaves. When the tractor ran out of gas, he went into my garage and grabbed a gas can that i had used to contain old gas that had been drained from my 2cycle echo weedeaters, shindaiwa blowers, stihl stick edgers and even my 4 cycle push mower. This fuel was old. So, he added about 1 1/2 gal. of the old gas/oil fuel to the John Deere and said he ran the tractor for about 10 minutes (some of the time was at idle) while he was cleaning the tractor to put it away in the garage. My questions are... What damage has potentially been done to my Kawasaki 4cycle engine? (He said it ran fine with the "bad fuel"). What should I do at this point (after draining the tank)??? Change fuel filter? Change plugs? What about the fuel in carburator??? Until this stupid episode, I was getting ready to put the John Deere away for the winter. I have recently stopped draining the gas/fuel from my lawn equipment when winterizing. Instead, I just fill the tank(s) with fresh gasoline mixed at the proper ratio with SEAFOAM (a "stabil" type product). I have used Seafoam with pretty good results as it is not only a stabilizer/winterizer, it also has some important engine cleaning ingredients. Oh well............now what do I do?