Per the gasket manufacturers, gaskets go in dry.

Or if you think you know more than the guys who designed the gasket, go ahead and slather it with goop.

What the goop does is provide another liquid layer between gasket and surface.

The last engine I took apart had some sort of graphite colored stuff on each side of the gasket. It took real effort to scrape it all off the block and heads.

Note: There are some gasket holes on some engines that tend to leak either oil or water. On these engines, a light coating of Hylomar Blue just around the offending holes will keep the assembly from leaking.

R.