8 years ago when i got my used truck i went with a set of westin black-painted std steel step bars. i noticed the insides were unpainted and knowing that most rotten step bars id seen seem to rust from the inside out, i thought id try painting the insides. i poured 1/2 a qt of black rustoleum paint inside each one, turned them, tilted them back and forth, trying my best to coat the inside of a 3" pipe that i couldnt see. put them on and kept up with the outside as best as i could, waxing in the summer, painting any rusty spots, running huge front mud flaps to try and keep gravel damage at bay. took them off this week because i had noticed the step pads were loose and under the drivers side one there was a rust hole, knocked on them with a shot hammer and poured all sorts of rusty wet crap out. found a few pinholes i was unaware of. im going to completely sand the outside and im wondering what i could pour inside. liquid bedliner? construction expanding foam? or should i just let be and be glad ive gotton 8 years out of a non-stainless step bar set? im not sure what the normal service life for a product like this is, my truck is driven daily, year round, and they seem to salt 1/2" for every 1/4" of snow we get around here. im thinking construction foam would just hold water like a sponge, dont know how well bedliner would stick, i cant prep the inside like you can a truck bed. if it wouldnt take so much to do, id almost consider putting a grease fitting on and fill them with grease, i considered used motor oil if i could indeed completely seal it up. anyone tried anything that worked? or by the time they rotted through it was time to get another truck anyhow? i doubt i'l have it another 8 years, so im thinking of trying to make what i have go a few more years.