Well depending on how old the gasket is and how worn it is you can't really re-use it. You can go to the autoparts store and pick up a new one but a high temp sealant works as well if you have it laying around. Most egr gaskets I've ran into I was not able to re-use the gasket and even if it were still usable I wouldn't use it. Its better to buy a new one or use high temp sealant. I wouldn't re-use a gasket on anything.