Amen, George. I use motor oil (lightly).
Just make sure you don't get crazy or it will mess up the head to block seal. I like to run the bolts in before I put the head on with lots of oil. I pull them out and wipe them with a clean cloth and repeat several times. Gives me the opportunity to see if I have problems before I get too far.

Also, you may have bumps on either the head or block from minor corrosion around the water jacket ports that is causing the head to "stand-off" from the block when you have it torqued down properly. A mill file carefully and lightly stroked across the block will knock any of those down (after thorough scraping of gasket or goop).

Have your block deck checked (straight edge across cylinders, a REALLY straight bar) for a low spot between cylinders. More than .002" is very difficult for the gasket to fill properly. Unfortunately, repair of that requires a complete rebuild so the block can be decked.

Mike!