I want to set something straight, When your truck had blow by does that mean that your piston rins are blown?

 

All pistons have a certain degree of blow-by ... that's why you have a PCV system. What they're talking about is the gas/air mixture "blowing by" the rings into the crankcase. Oil can go the other way when the rings have worn the cylinder enough. The oil control ring can no longer scrape the oil off the wall ... resulting in oil bypass into the combustion chamber.

 

the rings are worn out or the cylinder bore is worn to the point that the rings cannot seal against the wall.