Here's my Vermont two cents worth on undercoating:
- Spray on rubberized coatings tend to cover the rust
and do nothing to kill it. Over time it will chip or
peel and end up trapping salt and making your bus
rust faster than if it had not been undercoated!
- The best thing some of us up here have found is quality
bar and chain oil. Do not get the cheap stuff. Agway
or Husquarvarna seem to both use similar formulas.
That is a mixture of phosphoric acid, oil, and paraffin.
The phosphoric kills the rust. In fact the rust will turn
black within a week. The oil and wax leave behind a sticky
residue. This treatment also has the advantage of
lubricating all joints, etc...
- When looking to buy bar and chain oil, READ THE LABEL.
Although it won't give you the ingredients, it should
say something like: High adhesiveness, high oiliness,
High Film Strength, Anti-Rust.
- The best way we have found to apply the bar and chain
oil is with a 3M Rocker Schutz gun and an air
compressor at about 50-60 PSI. Atomizing the oil
helps to make this a quick job as well as makes it
possible to spray into doors, rockers, etc.
- This stuff will evaporate/dry to some extent and leave
a thin film behind.
- I do my cars twice a year.
In the fall, and also in the spring.
- It's a good idea to pressure wash your ride and let it dry
before undercoating. Spraying the oil on top of mud won't
do much good...
- I spray all sheet metal, joints etc underneath, and also
spray in the rocker panels, doors, etc.
- Would you rather have salt water or oil in them door seams ?
Remember you'll be splashing up slush that seems to
get inside all seams (this salt mix is not nice !)
- Unlike the rubberized stuff that does nothing to kill rust,
you get a chemical reaction from the bar oil with the metal
which forms a protective oxide.
- This treatment is for cars driven daily in the rust belt.
- Considering the cost ($5 a gallon) this is economical.
If you are judicious in applying this stuff, one gallon
is all you need.
CAVEAT:
BE CAREFUL WITH ANY UNDERCOATING YOU APPLY.
DO NOT SPRAY IT ON THE EXHAUST OR ENGINE !
GIVE IT TIME TO "DRIP DRY".
YOU DON'T WANT A BURNIN' BUS.
