I'll chime in here with my experience. When I tore my motor down all the oil rings were collapsed inside the piston groove. Jerry Lemond and I spoke at great lengths concerning the issue. He advised me to check the new pistons and count how many oiling holes were in the oil ring groove. There were only four. This meant the pistons were the old design and not the newer modified design. The difference is the newer design has four additional holes drilled in them as close to the wrist pins as possible where the metal is thin. I had the machine shop do this modification. The next step in the process, per Jerry, was to break in the engine and start running 5W 40 synthetic diesel oil I think he suggested
Rotella. I only have about 450 miles on my build at the moment so it is too early to tell how it will work out and (unfortunately) the skill level of the machine shop to build an Isuzu motor is becoming questionable. Jerry tells me that new crate motors from Isuzu have the modified pistons in the. If I had to doi it over again I would have Jerry get me a crate engine. The other thing to not is Isuzu does not sell oversized pistons and rings. I had to go with the aftermarket to get pistons which was one of the few non-OEM parts I had to purchase.
And FWIW, I have had issues with other vehicles sucking oil into the intake. I had a Z06 that would do that if you got the RPMs up (though I would NEVER do that

). Several companies created oil catch can systems that would prevent the oil from getting into the intake. The more often you did (ahem) spirited driving the more often you had to empty the catch can.
Just my 2 cents worth to the discussion.