I have a Jeep Wrangler, and you can see quite a bit of the under-carriage. So, for cosmetic reasons, and to keep down the inevitable rust, I use this product:

http://solutions9.3m.com/wps/portal/3M/en_US/3MAutomotive/Aftermarket/Products/Product-Catalog/?PC_7_RJH9U5230GE3E02LECFTDQCEK3_nid=1WGT0QN08Sgs6DTWTJQPBBgl19MNFMCQP3bl

On the motor, brakes, anything hot, etc, I use flat black high heat paint, (spray), whatever brand they have at the auto store.

I do this about 4 times a year, and it really makes the Jeep look great.

You don't do the underseal that often, do you?

4X per year?!?!?!? Do you drive your Jeep in an open-pit salt mine?

I understand the 4x per year. I had a friend in Quebec that used to do the underseal twice a year and was not enough.

Depending where we live weather conditions, salted roads, etc, can be realy bad.

I may try silver colour as it allows me to see any corrosion or leakage easily. Thank you.

yep....Quebec roads == Open pit salt mine (but with lots of potholes)

Do you clean off the old underseal before re-applying? If so, how? If not, you must have half a ton of rubber hanging under the Jeep!

check out POR 15

will not do exhaust, but resistant to abrasion, impact, corrosion and chemical

www.por15.com

I like POR15; but it is a bit pricey and takes a bit of effort to apply.

For routine rust spots that show up under my Toyota pickup every year after I go to the Speedweek event on the Bonneville Salt flats I use Rustoleum rusty metal primer. This won't work on exhaust systems and may not last long on brake drums that get hot from heavy use. I usually I usually give the surfaces a good detergent pressure washing and when dry brush the primer on right from the can. I resort to the spray can application only where brush application is difficult. After 8 years of this I'm staying pretty well ahead of the rust.

Ed Weldon

Indeed, the POR15 is the favourite of people who likes to restore their old cars

http://www.holden.co.uk/displayproduct.asp?sg=&pgCode=&sgName=&pgName=&agCode=&agName=&pCode=094.930

I'll give it a try. thank you all.

And it looks like POR15 also has a paint for high temperatures (engine, exhaust, etc)

Check out the products sold by Frost Auto Restoration. I don't know where you are but they sell by mail order & a lot of their products seem to be from the USA.

If cost is not a problem, then a Polyol truck bed spray liner is a permanent solution, if area is properly prepped before spraying. The military even uses this as armor.Good stuff.

Wurth has a product called Rust Guard that can be painted or sprayed, although I wouldn't spray it if you have a valuable gun. Once it sets up it is extremely difficult to remove. I have used it on floor and trunk pans during restorations. After all the tools and hammer dollies have been tossed around on the floor, NO chipped paint. The instructions prefer that you not remove all the rust and that you poke a small hole in the lid to pour out, do not shake or stir and if you do open the lid, cover the lip with waxed paper or you will not be able to remove the lid again. GREAT STUFF!!! A little over $100 a gallon the last time I bought it (1999).

High heat black stove paint or Aluminium paint.