I treated the inside floor pans with Por-15 with a brush and it worked fairly well, however when it comes to underneath the car i cant imagine brushing is going to get at all the areas. Can anyone recommend a product in a spray can for under the vehicle? I saw that zero rust has some in a can, also what about the eastwoods rust products? I saw that rust-oleum also has an epoxy paint for appliances, i wonder if that would work for under the vehicle after some POR-15 metal prep is applied? I believe the POR-15 metal prep is a rust converter aswell as an etching agent to help paint stick, so regardless of the paint under the car i will likely still use metal prep.
Treating undercarriage
- Thread starter Trivium91
- Start date
I'm using a paint on Gempler's rust converter and Amsoil metal protector HD for my surface rust. Only the latter is in a spray can though.
Beware of any rubber painted "coating" type protectants, they rarely adhere well enough to stop moisture from getting behind them and quietly rotting your car. I prefer these cosmoline style coatings...
Beware of any rubber painted "coating" type protectants, they rarely adhere well enough to stop moisture from getting behind them and quietly rotting your car. I prefer these cosmoline style coatings...
hmm looks like i can easily get the "zero rust" products in my area, they have both a gallon and spray cans and a metal prep product to use before hand. I can brush on the easy areas and spray the crevices.... Anyone try zero rust? Going to be a lot of work with a wire brush though and all that painting under the car.
Regarding the rubber products, that makes sense. Anytime i look under a vehicle with rubber undercoatings they seem to always rust under the product...seems like it traps condensation more than anything else.
Mikes5thAve
Well-Known Member
I always get everything oil under coated.
Hard under coating is only good if vehicles are new. If there is any spot where it's started to rust already or where there is anything scrape or chip or damage to the paint at all it only ends up trapping moisture and causing rust like you said.
POR15 and other paint like that is only as good as the prep work before it is applied. Depending on how bad the rust was before it was cleaned up and the paint is applied it can continue rusting under the paint like there's no protection at all. Im working on a trailer now that has problems from that.
Hard under coating is only good if vehicles are new. If there is any spot where it's started to rust already or where there is anything scrape or chip or damage to the paint at all it only ends up trapping moisture and causing rust like you said.
POR15 and other paint like that is only as good as the prep work before it is applied. Depending on how bad the rust was before it was cleaned up and the paint is applied it can continue rusting under the paint like there's no protection at all. Im working on a trailer now that has problems from that.
Trailer is powder coated? I've seen how things can rust from powdercoating under. I was actually thinking about using boiled linseed oil under the car but how often would you need to apply it? Seems like it would make a huge mess, plus if you ever wanted to paint it after would be extremely hard to remove all the oil. So far in the hard to reach areas i applied some motorcycle chain oil in the higher up areas, than i used 3M cavity wax because its very expensive in the rocker panels and lower regions.
Mikes5thAve
Well-Known Member
No it's an older one that the previous owner cleaned up and POR15d. it is now scabbing and flaking off in various places. I don't know how much prep work was done so I'm not blaming the product I'm just using that as an example since it's one more thing I'm dealing with right now.
You can get various undercoating oils in bulk and spray can. Check out what Canadian Tire has if you can still go into the stores out your way. Rust Check has a think version for top areas and thicker stuff for underneath. Krown probably does too. Both are pretty similar. They usually have other stuff too both spray can and in bulk. Parts stores can get the same stuff but Canadian Tire usually has some small supply already there instead of having to order it.
You can get various undercoating oils in bulk and spray can. Check out what Canadian Tire has if you can still go into the stores out your way. Rust Check has a think version for top areas and thicker stuff for underneath. Krown probably does too. Both are pretty similar. They usually have other stuff too both spray can and in bulk. Parts stores can get the same stuff but Canadian Tire usually has some small supply already there instead of having to order it.
Hmm i was looking at "fluid film", i hardly wash under the car with a wand so imagine it will stay on for a while. I try to always drive the car on the nice days but sometimes it rains that you cant predict it. I can always just re-apply the fluid film once a year.
So that begs the question now should i use a rust converter before i apply something like fluid film? Maybe hit everything with a hand wire brush before i use the rust converter? A black chassis sure looks nice but no one really ever sees it other than me. Or should i just apply the oil and say screw it.
Mikes5thAve
Well-Known Member
That's when it all comes down to opinion. I've always gone the oil route and never bothered with converter. Just about all of those oil products were formulated to prevent rust with winter driving and when they pretty much stop rust in it's tracks in those harsh conditions it's good enough to keep it under control for the rest of the time. I usually get the cars that don't see winter done every few years and it lasts long enough to still protect things.
I've got a project now that has the southern style rust in the wheel wells and some other places and I haevn't decided yet if I want to go the rust converter route on it or not. I think I'll do a mix of both.
I've got a project now that has the southern style rust in the wheel wells and some other places and I haevn't decided yet if I want to go the rust converter route on it or not. I think I'll do a mix of both.
cool thanks, black paint and what not would look the best underneath but i've read alot of things about it not working long term like you said. In fact i know the floor pans of the car from the inside were painted and in good condition 10+ years ago...now they are rusted through in one spot...and rusting from the inside out even. The bottom has some surface rust in a few areas but thats about it...go figure it looks better under the car than inside. Bottom line is the products need to be applied properly, and unless i do a frame off restoration i dont think POR-15 is a great choice since its going to be extremely difficult to guarantee that every spot was prepared properly and sanded down. Perhaps this is why alot of paint jobs for the undercarriage fail. Its going to be extremely difficult to work under a vehicle with everything still attached, ensuring all crevices are sanded and cleaned for proper adhesion. I heard sandblasting POR-15 doesnt even remove it...so if it started rusted under the coating it would be a nightmare to remove. At any rate i have a Wagner electric sprayer, i think im going to spray down the undercarriage with converter for good measure than spray it with fluid film using the sprayer, like you said if i do it every few years i should be fine since it a summer weekend car.
Aspen500
Well-Known Member
Eastwood also makes a product you spray inside the frame rails and other hidden areas. They claim it converts the rust and seals it from oxygen so it can;t rust anymore. No oxygen=no oxidation.
Eastwood Internal Frame Anti-Rust Coating, 14 oz. Spray
Eastwood Internal Frame Anti-Rust Coating, 14 oz. Spray
