Well, I could be too for that matter. I'm just a machinist.

We have a finish requirement on the "skirt" which helps insure proper oil retention and many pistons are graphite coated on the "skirt" to aid in assembly. If you think about it, with the rings so high up toward the crown, the force of the power stroke and the the way the piston/rod assembly is made, how could you stop it?

The distance between the piston and the cylinder wall is so small that Ford matches pistons of different sizes (grades) to cylinders. Again, were talking MICRONS here. For example, with the piston I make (Ford 3.0 litre duratec) there are 3 "grades" (sizes) of pistons. the GREATEST diameter variation from the smallest grade to the largest would be 30 microns or just over a thousandth of an inch. There is no way it WON"T touch the walls.