[curtis73]

usually there is enough oil on the block that the gasket gets oiled that way, but you absolutely need to oil the gasket. Otherwise you can dislodge the gasket if it grips to the block when you turn it. They can also glaze to the block after 3000 miles and you'll be scraping rubber stuff off the block's mating surface.

The gasket seals because the pressure it exerts on the block, and in order to get that pressure, it needs to glide freely as it spins.

By the way, most oil filter manufacturers recommend FINGER tight, then 1/2 turn. Basically spin them on until the gasket contacts the block, then another 1/2. Not hand tight. Most of us just grab them with our hands and put them on hand tight which works fine.