Hi There,
Cork or composite gasket either one I always use sealer and yes you guessed it, Permatex Aviation Form a Gasket, good enough for Aircraft, always worked for me on anything I used it on, anyway make sure the bolt flange on your pan is good and flat, IE not deformed from over tightening, make sure everything is clean and dry, apply sealer to both sides of the gasket, start all the bolts and snug them up, not tight just yet, On sheet metal covers I always use a screwdriver/nut driver type handle to tighten the bolts up, start in the middle and do the crossover pattern a little at a time and go over the pattern several times, unless you're built like Arnold you shouldn't be able to over tighten the bolts with one hand, you want them tight but not tight enough to crush the gasket or deform the pan, and as mentioned previously in an hour or so the gasket will settle and you'll need to snug the bolts up again, depending on what I' doing I may check them several times before I call it good, Torque wrench is probably the best correct way, on a bench but in the vehicle they are cumbersome as there always seems to be something in the way, anyway that's how I've been doing it for years, Hope it helps, Good Luck, KillerDave