I recently purchased a 2006 F650 GT here in Tucson Az. Low mileage, only 14,000 on the odometer. looked great, ran good,,, I thought. Second day I had it I went for a ride, driving along enjoying the great weather in Az. I noticed spots on my sun glasses, looked around and seen oil coming out around the top of where the gas tank used to be, it was running down the side of the engine too. I headed straight home and after taking The left cover off I found that the oil tank had split where it was bonded together. When I drained the oil it dropped out a little over FOUR QUARTS!! The old guy I bought it from evidently didn't look at the owners manual and checked it after it had set for a long time without starting it up until it warmed up and then checking it. I lucked out and found one on E-Bay for $79.00 ( new one is $179). My problem is I have never had a thumper and don't know what it is supposed to sound like. I am paranoid now and worry that it could be knocking and have some internal damage. like the manual says could happen with too over filling the oil. It is a sweet little bike I bought to explore on. I don't want to be out in the desert and have it blow up on me. Has anyone had any experience with over filling the oil? Any suggestions?