Best undercoat paint to treat bare metal with?

Still doing undercoat, over 2 weeks later. Its taken me long because when I come across a large rust spot, I will sand it off and then... well thats what this thread is about.

My normal procedure after sanding is rustoleum automotive primer then a coat of rustoleum bedliner. I then go over that bedliner with fluid film for even more protection, but this thread isn't about fluid film.

My last thread touched on this, and someone recommended por15. Does anyone have more recommendations on good undercoat paints? My only criteria is it isn't a rubberized finish because those have a few downsides that scare me away from them.

 

I personally would just primer then rustoleum paint, not the bedliner. paint is easier to touch up later. por15 is really good from what i read as well.

 

good points...touching up rust. Myself, went under my '97 4runner...and scoped it out. Overall, in pretty decent shape..only some very minor rust...which I cleaned up, and prime and re painted..jet black. My rig originally came from boulder, Co. but the previous 2 owners, took very good care of it..especially underneath.by spraying any debris , etc off...I'm not sure if Co, uses road salt...as some states use sand, or ashes, instead of salt. I've seen some 4Runners that came from areas that poured the salt on the roads, and many of 'em, were badly rusted...some,the frames were eaten thru...In fact, same could go for any SUV, coming from those areas...

 

I typically treat with a rust converter first; as added insurance of converting any oxidation that I might have missed.

Bedliner isn’t a terrible ideal as it offers some added chip resistance... but it has downsides too. Like that it can trap/hold on to dirt, and stain brown from mud/dirt over time (in other words, it can be tough to clean). I usually just use rustoleum satin black, then sometimes also top that with satin clear.