I use to dip the piston into a 3 lb. coffee can full of oil and ATF mix, I now squirt the same mix onto the rings in the ring lands and spin the rings around to make sure their lube well and wipe the excess off onto the piston skirts. I do wipe the cylinder walls off with white paper towels multiple times while assembling the motor and when degreeing the cam
I do use the same lube on the wrist pins and piston pin bores to lube them also