Best sealing valve cover gaskets
Start with covers that arent over torqued to begin with, as in straight.
Metal/stamped-Rtv cork gasket to cover..then with 1/4 ratchet...lightly snug them down and wait 20 min till they dry then just lightly torque with fingers on the ratchet, not your hairy palm, evenly center 1st then out to each outer like a upside down v ..then out to each end. Just like a head gasket...even.
If cast aluminum..use the moroso rubber over steel kind, the rest of the solid rubber gaskets out there are **** and will leak.