My non-factory steps have bolts in these holes. Don't know for the factory ones.

Indeed for your Krown guy. Most anti-rust shops don't give a rats ass about looking for access ports, they're paid by production, not quality.

Where I went for my truck, they used a grease instead of oil, and used already existing holes. When I asked them why, they replied ''Well, an oil will leak out, and we don't drill new oil, because that's just a new access port for rust to begin''

 

Where my factory steps where mounted through.

 

That is where my Lund steps bolt through as well. You could spray some junk in there but if you look, the rocker panel cavity is drained along the bottom. It will either just drain out or plug the drains causing a different problem.

 

I will have to see if my factory steps utilize the holes, they seems like large rectangular gaping holes though. I don't mind if it drips out a bit, I hate the fact Krown and similar applications drip everywhere for days but its really the only way to completely cover most of the metal, the thinner oils creeps and penetrates unlike grease or dripless product. dripless product doesn't find its way to even half of the places the juicy stuff does. What is more disturbing is that the rockers need drain holes to begin with so water must obviously find its way in there quite a bit. From where and why? always promoting rust by design it seems.... Jesus.

 

Those holes are for mounting factory and aftermarket accessories, primarily steps.

 

Thats where mine went through.