ReplaceGaskets

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.

Cleaning BOTH SURFACES THOROUGHLY cannot be stressed enough. "Gasket Remover" doesn't always work. Gently and patiently scraping away old gasket material with a knife or blade could result in scratching or gouging the surfaces and can cause permanent leaks. A circular Scotchbrite pad on the end of a drill or air tool works wonders for removing old gasket material and leaving both surfaces shiny and super smooth.

Note that these are custom made gaskets specific to the gs500.

OEM gaskets are a very good choice when replacing old leaky gaskets.

Aftermarket gaskets are available on eBay and other sites around the internet.

Don't use a cereal box! :) but, you can apparently buy "gasket material", as referenced in that webpage, and custom cut your own one properly.