Engine Coatings?

What coatings...inside the block(valley area), rods, cranks, pistons? The coatings for the rods and cranks are expensive plus the cost of shipping the part back and forth. There is not much to gain unless you spin past 7000rpm. The lifter valley and such serves two purposes as far as I know....one is to aid in oil drain back to the pan and the second is to seal up any loose or almost loose sand from the casting before it finds it's way into the oil.

Piston coating are suppose to do wonders and even the factory does it on their engines but all the guys I know(including me) don't do it. Mopars have great rod angles and tend to put less load on the skirts but with alot of people running 4inch cranks and killing the rod angle it might be worth the cost. Just my two cents.