With the forced pin oilers, I'm wondering if there are stress risers introduced, pre-disposing the pistons to fail at the oilers. Same idea goes for connecting rods - when they edm the oiling hole down the middle of the rod, if you don't extrude hone the passage, the rods crack and fail, starting at the hole. Short of extrude honing the pin oilers, it may be best to leave them out and look at other solutions for pin oil retention and longevity. Calico offers coatings for wrist pins as does Anatech, Ltd with their thin film diamond like carbon coatings, typically reserved for Ti valves. Another thing I have been looking at for some time is micro dimple formation. WPC Treatment does this (
www.wpctreatment.com).