Some makers even give a lifetime warranty on MLS gaskets e.g.
http://mr-gasket.com/mr-gasket-warranty.html. For the commonly used ACL gaskets ACL MonoTorque head gaskets have a 3 year 100,000km warranty while ACL Ezy-Fit head gaskets have a 12 month 20,000km warranty. Permaseal MLS gaskets are warranted for 3 years
http://www.aagaskets.com.au/PDF/AA00...20Warranty.pdf the Crossfire ones from the same company AAGASKETS from 30 days to 12 months
http://crossfiregaskets.com/terms.aspx.