In the past I've used Permatex's HD rubberized (non-drying) undercoating. It gave a pretty consistent near black textured finish that stayed mailable for several months.
Today I've tried 3m's HD undercoating. I think it's going to harden much quicker, which I don't care for and it's not quite black. It sprays out fairly brown and sits on the metal kind of dark gray.
I can't find the permatex anymore, so I'm looking for other options. Anyone tried something they liked?

 

I just used POR-15 gloss black for my truck. It came out beautiful on the frame and inside wheel wells. It came out a very very nice glossy textured black. And so far it's waterproof so it means no rust for my frame ever again!

 

recently did POR-15 as well ....just be careful you don't get it on you....you'll wear it for awhile

used a brush and a gun...really almost prefer the brush , goes on nice with a brush...can't see brush lines once dry either.

 

I have tried the Zep Rub Coat and find that it performs fairly well. It is thicker than the stuff you get at Home Depot. I do not know how it stands up against the Permatex HD though.

 

I am a big fan of either the 3M or Rustoleum products although it may be a little bit of work and may not be as durable as some of the more expensive products, you will wind up saving yourself a lot of money.

 

I used Chassis saver Paint Over Rust to Stop Rust Permanently With Chassis Saver Truck & Auto Underbody Coating. I used satin black - the yellow mustang one. It took me four days and six paint brushes but I really took my time and got every part. It also needs to be mixed (about) 10% with MAGNET PAINT CO. CHASSIS SAVER S8-01 S8 MULTI-TEMP REDUCER GALLON. It will fade in direct sunlight so needs to be painted over with black spray paint - in direct sunlight areas. Yes it is about $100 a gallon (my truck took about 3/4 of a gallon). I did it last summer and it has not chipped, cracked, or failed. I painted every brake line, fuel line, wire, nut, bolt, hose, cable, everything. Takes devotion but I love my truck. Will not come off skin or clothing or hair for like three weeks or longer.

 

I bought my truck used and the previous owner had the frame and most exposed parts rhino lined or lizard skinned (I can't find a tag but has the same texture) and there's not a speck of rust or cracks anywhere. I would suggest some of the bed liner material as it seems to work pretty well.

 

That stuff looks very much like POR-15. I agree that stuff works great as long as there is rust for it to adhere to. Using it over bare metal or other paints it doesn't hold up as well and will peal off.

Looks like you did a great job on yours! In the last pic you can see the rust in the hole that a brush won't get into. Even for this stuff a throw away $20 sprayer will get it in more cracks, holes, corners that you can't get to with a brush.

 

A one year update. The Chassis saver "paint" held up great for a few months. Recently I am noticing some rust bleeding through and some pitting. Some areas look brownish. I have powerwashed the underside well and I plan on another coat. Will post another update in a bit.

 

POR leaves pinholes that eventually bleed rust. A second coat normally fills in these pinholes and normally makes it a 100% job for many years.

 

I want to also paint the cab floor this time. Just reading back I noticed you said the metallic type paint does not hold up as well on bare metal. Anyone wanna suggest what should be used? I would also like to put the paint in a sprayer this time. Faster, better, easier. And maybe just some rattle can rust preventing paint for the cab floor.

 

Just a lil thing extra to add into this...

If using a rubberized coating...Please take some extra time and after sanding.....Use a mini propane torch to pass over the metal fairly quickly...TO evaporate the moisture completely....Then, Use the brush, etc....Also, the extra bit of heat will help the coating to adhere to the metal much better.....

Just a thought....TO eliminate the metal from rusting away BEHIND the coating....

 

What if you get either of these products on bolt threads? can you still remove the nut or bolt? if you needed to replace a part that is.

 

It take more effort but the bolt heads will still accept a socket or wrench. You need to 'walk' the socket onto the nut or bolt though.

Yesterday I brushed on some more oil where I didn't spray behind the front bumper on my X. When I was originally spraying the waste oil I didn't want to get it all over the bumper because I knew I was going to be cutting, welding, and painting it.