Two things are also very important to making the pan gaske do its thing.
- Torque value: you need a constant - even force all the way around the pan. Make sure you use a torque wrench.
- Torque pattern: You need to tighten the bolts in a specific pattern so the applied loads are equally distributed. Look to an old shop manual and you'll see an "X" pattern is used. Follow it.
Over-torquing the bolts will distort the pan base. When that happens, you'll never get it to seal. Not torquing in a specified pattern will compress one area more than another and again, you'll never get it to seal.
Paul