My 03 Tahoe has a little bit of surface rust underneath on the axles and some on the frame.  In the coming few weeks I plan on pressure washing and wire wheeling/brushing all of the rust off and giving it a 3 part POR15 treatment.  Degreaser, cleaner/etcher, and the POR15 itself.  Does anyone have experience with cleaning up rust from the undercarriage and with this product?  It's a little pricey, about $300 for the kit but I think it will last much longer than repeatedly hitting it with rustoleum.

Don't get it on your skin - you'll have black splotches for weeks until it comes off.

Preparation is everything - if you can get all the rust off & get it down to smooth bare metal you will have a nice gloss black finish that is virtually indestructible.
If you just want to slap it right over the top of the rust you will see all the pits in the metal when it dries.

Stuff works great. Just don't let it touch your skin.

I just did the rear frame of my 1997 k2500 truck. I removed the bed, and wire wheeled off the easy spots. I have a 2700 PSI pressure washer and the 0 degree tip does a good job on removing heavy flakes.

I used their metal prep spray and it really doesn't seem to do much to flaky or thick rust. I used a spray bottle and applied it for about an hour and a half. I didn't see tons of rust eaten off but hopefully it prepped it better for the por-15.


I hand painted the frame rails and the crossmembers, as well as the shock mounts. It takes a very very long time. I couldn't imagine laying under a vehicle trying to do the same and hitting all the spots. I used 1 quart on the rear frame and it was like $45 from amazon.

It dries to a very hard like plastic coating and looks pretty tough. I think for this stuff to really work it needs to totally cover a rusty frame to avoid water destroying it and bubbling.

WEAR Safety glasses and cover up very good, it stains your skin black and doesn't come off for a week, it would really suck getting a big drop on your face! The paint is pretty thin so it spatters when brushing is why i put the glasses in bold.

For top coat I used my other go-to rust paint. Rust-Oleum HAMMERED finish paint. Its great paint much better than the basic paint that rust bleeds right back through. I usually use only the hammered on rusty frames and it has stayed on everything even applied directly over rust. I just spray it on with a cheapo $10 harbor freight paint gun, thin the paint 50/50 with only Xylol/xylene (sold by the acetone and lacquer thinners) It sprays great and dries in 15 minutes. I have found this paint to be very durable as well. Its $11 a quart vs $45 for por-15 and honestly I don't know if its much worse. Time will tell. It was my first use of por-15.

Edit the Rusoleum Hammered paint is UV safe is why I coated the por15 with it, I painted my fathers trailer and it still looks pretty good 5 or 6 years later and the rust still hasnt come back.

Yes, I plan on basically wearing a chemical suit to do this.  I really need to find an individual or a shop where I can get the truck up on a lift so I can get under it standing up and adjust the height so I can wire wheel it, pressure wash it and do everything the right way.