Has anyone undercoated their Stang?

I crawled under the car today and noticed that over 90% of the bottom of the car itself is unpainted. I can just see the hot-dipped coating and body sealer. It will take me a long time (and lots of messy paint) to seal it all up with Rustoleum and a brush. I don't plan to drive it in the snow or rain, so is it worth it to spend all that time coating the bottom?

I bought the tar-like undercoating at the dealership for my 00 Vic (since it is a daily driver) and noticed that some parts still didn't get coated with the tar.

Do I dare trust the Ford rustproofing technology with MI weather (but not driven in snow/rain)?

 

I rust-proofed my Stang ... using Krylon RustTough Primer spray, and then Enamel spray over that, all over the unpainted bottom of the car. I felt that using Rustoleum/tar would not work as well - if moisture gets between the tar coating and the metal, it would actually turn out worse than not having the coating of tar - and, it hides rusting, so you wouldn't know if the metal underneath is rusting badly until it's too late.

I decided to go with the lighter sprays, figuring that it would provide some level of protection. I can rinse off any dirt, etc. from the coating pretty easily, and I can add layers of enamel easily yearly.

 

Has anyone reported rusting on the bottom of the S197s when driven year-round (snow/salt)?

 

Newer cars don't really rust in areas they are not designed to. I am not sure why Ford decided to leave the rear axle unfinished, but the surface rust doesn't hurt anything. Cars typically do not need undercoating anymore, but you can do it to reduce noise a bit. We don't even offer undercoating anymore, but the best place to go is to a Ziebart outlet. They do professional rust prevention and sound deadening.

 

Like Kevin said its not necissary to undercoat. Anything unpainted is most likly ss. Discoloration/surface rust is nothing harmful anyway.

 

I wouldn't undercoat, especially if you are not going to drive it in winter weather. One problem that undercoating can cause is that it can trap moisture.

 

I RustCheck'd mine the fall before last because I had to drive one winter without a winter beater. This site will explain how it works http://rustcheck.com/. I was going to do it anyways even if I didn't winter drive it as it allows the oil to creep into all the crevasses to help displace water. I didn't do it last winter but I still have some slight oil film coming from seams still.
The disadvantages are; you're supposed to reapply it every year to get full warranty; it drips from your car for a couple of weeks; if you apply at the wrong time of the year in dusty conditions your engine compartment will look very dusty. You can always detail your car a month later and it'll look good again.
It has a cherry scent so it doesn't smell bad. It'll ooze out of the door handles, keyholes, under-hood seams, door sills, door drains, etc, basically everywhere they shoot it. I actually like that because I can tell it's doing it's job. After they apply it you wait about 48 hours for it to creep and then you wash your car a couple of times and it'll look as good as when before you took it there.

 

I always here the trap moisture thing, so when a droplet of water stays wet for 25 years under the undercoating it would be a problem? Thats an old wives tale as its one of daddy's standard reflex responses to salespeople handed down over the years. I'm just looking is another one, the most annoying one ever is '$$ cash right now!'(every single car deal is a cash deal-that goes back to the feed stores of the 18th century)... I hear the same 25 or so expressions verbatim about 8.5 million times per year. It does not trap moisture, even if you hosed the car down and immediately undercoated it. Paint doesn't trap moisture, spray in bedliners don't trap moisture.