Oil leak at valve covers

Get a set of aluminum cast valve covers. I use the Felpro rubber/cork. I wouldn't torque them, use a nut driver or old speed handle. I run the bolts down till I feel contact, then just a little more. After one heat cycle, I go back over them and give them just a little more. I have had the same gaskets for 4 years, and have had the covers off multiple times, no leaks.
Steel valve covers, not straight and overtightened, will leak every time. Just don't over do it.