October 2014 I bought a 2004 Florida Wrangler TJ- not a speck or rust anywhere including frame and chassis parts. The 10 year old factory black paint on the frame and chassis was very thin. I sprayed it all with Rustoleum glass black. Let it dry for a couple weeks and ordered 4 cans of FF with the flexible wand. Let me add that before painting, I drilled a couple large water drain holes in the problem areas of the frame. Jeep owners know where these are. I also removed the front bumper to allow prime access to the front of the frame. Sprayed the FF inside all the frame access holes, as well as coating the entire frame and chassis parts including brake calipers, E brake cable ends, ujoints, etc. Has to work fast as I really could have used another can. However I was able to cover the areas listed. During the winter I was torn about washing the Jeep as I didn't want to remove the FF. however it was such a miserable nasty winter I couldn't take an ugly vehicle covered in gray slush and salt. Therefore I washed it every other Saturday, using the drive through laser wash which dl so sprays the undercarriage. In the spring, I thoroughly sprayed the underneath with the high pressure wand, including the inside of the box frame through every access hole. Fast forward one year, to yesterday. I crawled underneath to inspect and apply this years FF. There is still no evidence of ANY rust forming, and touching any part of the chassis leaves an oily residue on your finger. Also, reaching in through the frame access holes you can still (even after the pressure washing with soap) feel a thick greasy layer of protectant. This year I sprayed even further, including battery posts, AC fittings that were begining to oxidize, lower radiator tank, etcetera. I am sold on fluid film. I used 4 cans on the wrangler, so I would estimate 6-8 on a full size pickup. Add another for plow.