What is generally the shelf life (still in packaging) of rubber o rings and gaskets (like an engine rebuild kit)?

I found a chart online that has the specific names of different kinds of rubbers and their shelf life, but i don't know what kind of rubber is used in, say, an oil pan gasket or distributor o ring. The only rubber I recognized is Viton and that has unlimited shelf life.

I happened across an old unused gasket kit for cheap, the viton valve seals alone are worth what I payed but I'm trying to find if I can use the rest of the kit

 

theyll be fine, they wear when exposed to operating temps

 

Thanks bro