I went to the "Fluid Film" web site and have to say what a joke!
Here is their video for their product. While it does have it's good points you NEVER use a liquid non hardening rust inhibitor on exterior or inside body panels. All liquids attract and hold dirt. This in turn attracts and holds moisture. A buddy of mine that owns a body shop loves these products. Why, it brings him rust work and lots of cash!
Russ told me about a guy that brought his 3 year old car in saying it sounds like there is water in my door! Sure enough the door had about 3" of water in it. Why, the weep or drain holes had all been blocked by dirt do to him (customer) pouring oil inside his doors! Russ charged him $500 to clean all the doors and told the guy to stop using oil as a rust inhibitor.
But it's your dime and you can get the job done right at Z-Bart or any real (not a car dealer) rust proofing shop or you can do what the OP did and pay 10X the cost of having it done right the first time. Note I'm not slamming the OP everyone love to save money. But I have found 99% of the time if the deal is to good to be true, then it most likely will cost you in the end.
Don