ive only ever bought one used engine of ebay big risk but i needed a spare got a rbws7111 with claimed 2 gallons on it for £30 when it arrived not sure if the guy mixed up the engines he was selling but mine looked to have been just broken in not a mark on it at all inside or out and still hada use the screwdriver when flywheel jammed. anyway used it for 7 gallons throughout end of summer series last year and all of winter series and never had one bit of bother at all i now use it in my backup car still has good punch best £30 i ever spent lol