[Rick Parker]

The key to the puzzle of most gasket failures it to keep the fastener (bolt/stud) stretched enough to maintain the elastic forces upon the gasket.
If the fastener is stretched beyond its yield point it will fail structurally and as a result will be unable to maintain clamping force. Many of the gaskets being used in OEM (other than head gaskets) are plastic framed with a rubber ring that has two small raised lines that provide 2 effective seals. This design works very well on freshly machined clean surfaces, and dissimilar (sp?) metals. The resilence of the rubber is more effective in providing an effective seal without followup retorquing required with aftermarket fiber gaskets. Overheating will damage OEM type gaskets, where fiber type can accept more heat but initially require retorquing.