Valve Cover Gaskets
 

Cork vs Rubber, Who likes what and why?

AND do you like to apply additional sealant?
what type?

I prefer cork but Felpro makes a really nice neoprene gasket with a metal stiffener in the center. They're around 40 bucks but last forever.

I have the rubber/steel ones. installed dry, no leaks, reuseable, no complaints.

Dont mess around get the rubber gaskets I'm still using mine from 5 years ago and thats taking them on and off about 4 times a year. (cant leave anything alone) Cork gets hard and brittle I found in a couple of years. I like to clean with brake cleaner or carb cleaner, put some on a rag and wipe the surface of the two contact areas and install dry.

P.S the steel inserts are great you can never over tighten them and squish the rubber out :D

Unless you plan on removing them on a regular basis, I'd through away the gaskets and use Permatex Ultra Copper gasket material (red RTV). My old truck had the hardest covers to seal until I used that stuff. Drove it for 80k miles with out a leak. I wouldn't use anything else.