I tried those thinkin I had found the end all be all. I even got the fiber reinforced ones. I used one on the thermostat housing and valve cover. Torqued to their specs. The valve cover leaked really bad. Thermostat housing not as bad but it leaked. I went a little tighter on torque. Still leaked but it helped some. A little tighter still. Still leaked. So I put a standard cork valve cover gasket on and a blue FelPro thermostat gasket and no leaks. I hoped I had found something, because nobody makes a nice reusable valve cover gasket for a slant 6. I couldn't get them to work for me.
