The tank had some minor surface rust, so I decided to KREEM it. It's expensive, messy and annoying, but it works. NOTE: Make sure to not cover the vent that's on the lid. It's the little triangle shaped bump. If this gets clogged, the gas won't flow and you'll be stranded on the side of the road. Yes, I learned that the hard way. I used copper spray a gasket on all of the new gaskets. I'm still not sure if it was good to use it on the side crankcase covers, but it was recommended by many people online.