Replace Gaskets

These are kinda like washers that keep bolted-together engine parts from leaking oil. If you have leaking oil from a seam, you may need to take apart, clean up the edges, and replace the old worn gasket. Note that these are custom made gaskets specific to the gs500.

Orrr.. you can use liquid gasket, if you're an artist.

Dont use a cereal box! :) but, you can apparently buy "gasket material", as referenced in that webpage, and custom cut your own one properly.