Mine are gray and came from Cummins. I've had them for about 120K miles and they've been off and back on 3 times for valve adjustments and they still don't leak.
Scott
Torquing does not do anything. The bolts have shoulders on them to set the valve covers the proper distance from the head to avoid cutting the gaskets. More torque only presses harder on the bolt shoulder. They only need to be tight enough to keep from vibrating loose.
I have yet to see how anyone can have a problem with the grey gaskets. I just put them on the valve cover, then install the entire "assebly" onto the engine. No slippage, no leaks, and they have been on and off plenty of times for one reason or another. I had some black ones a long time ago, and dont seem to remember any problem with them. I never trusted myself to line up the black ones correctly either- I put them on the VC first, then put it on the engine.
Daniel
I wonder if the swelling has anything to do with the type of oil used?