Here's my technique: I wash and degrease the pan, bolts, and gasket surface of the transmission, making sure all gasket surfaces are clean and oil-free. This takes extra effort, but is well worth it. I apply the new gasket to the pan dry (I do not moisten with ATF or use any kind of sealant). With the pan seated on the transmission, all six bolts are fastened finger-tight. Then I torque the bolts to 8Nm, staring with the sides first and then the corners in a crisscross pattern. I will make a second pass with the torque wrench to double check tightness.

It is also important not to overfill the transmission, which can cause leaks. If the ATF fluid is not quite operating temperature (between 20-30C) it should measure about 12mm below the Min. mark on the dipstick.