Auto Rust-Preventive Treatments, Undercoating, Internal Anti-Rust Agents


1 MW
Apr 19, 2007
Buffalo, New York USA
New car with 400 miles. What goes wrong where I live, Buffalo NY. Is rust. Rust caused by salt on the streets in the winter. Salt is used to melt the ice. Steel is a stupid material to build a car from.

Took car all apart. Plastic covers on bottom, There was a giant carpet like cover on the bottom. Remove wheel wells, bumpers, lights, door panels, some of the interior and all parts so I can see and spray the steel body. will take pictures when I get the camera fired up.

Here is some information from
View attachment Rust-Preventive Treatments General Information.pdf
View attachment Rust-Preventive Treatments - Undercoating Areas.pdf
View attachment Rust-Preventive Treatments - Areas to be Covered by Internal Anti-Rust Agents.pdf

Car was built in Mexico. See undercoating that looks like it was applied with a brush from the dollar store. Looks like they forgot to apply undercoating to the bottom of the place where spare tire goes. Plan is to apply this stuff with a brush from the dollar store.
3M™ No Cleanup High Coverage Body Schutz Coating 08964
What goes wrong with this type of undercoating is clogging up drain holes. Will be careful not to do that. Will only put it on the bottom of the place where spare tire goes.

Next will spray oil everywhere and inside of all sheet metal up to about the windows. It will be a sad day when the roof rusts. Theory is oil prevents steel from rusting, same as the steel parts inside the engine. Looking for suggestions on what type of oil or grease to spray and how to spray it? Years ago when I did this to a different vehicle, I called a oil, grease supply guy. He told me that he was selling oil to the places that do rust proofing. Here is one local place.
Go to the web site to see how they drill holes and spray inside body with long hoses. Spending a week taking the car all apart seems like a way better way to apply oil and see where ya are spraying.

Oil, grease supply guy said he was selling vegetable oil to the places that do rust proofing and it was not the best product to prevent rust. Rust proofing places use it because it is less harmful to breathe and it don't smell that bad. He sold me a 5 gallon pail of this:
Texaco Rust Proof Compound L
Here is a link to data sheet:

Texaco Rust Proof Compound L looks feels and smells like grease. Oil, grease supply guy said to thin it with "good quality paint thinner" so I can spray it. In the past I have used this sprayer:
Snap-on, Gun, Air-Solvent (Blue-Point®) GA299
What goes wrong when crawling around under a car or truck with this sprayer and the rubber hose in a bucket of thinned grease is I accidentally kick the bucket over :( Also don't think this tool is good for spraying grease because I need to thin it too much. Worried that if spray is thinned too much it won't stay where I spray it and will run down due to gravity.

Here in the attached Honda PDF files I see some type of oil sprayer.

I got very little knowledge of paint / oil sprayers. Do have a air compressor. Whats the best way to spray this [Texaco Rust Proof Compound L] that has the consistency of grease. Have tried heating this stuff in a crock pot. That didn't work.
Still learning about spraying different liquids. Went to the furniture finish guy. He gave me a spray gun that is missing the pot.
Devilbiss JGA-502
Here is a picture I stole from eBay.
View attachment 1
Will rig up a new pot made from a metal soup can?
That was my gun of choice for the first 15 or 20 years I was in the collision repair business. I think I had about 6 or 7 of them all together but I only have two left because I sold the rest of them at yard sales. I was using the ones I have left to spray guide coat but now I use an aerosol guide coat because it's quicker and easier.

The old JGA502 was great in it's day but I wouldn't use it for anything but primer or guide coat these days. I believe you can still buy parts for them but you'd probably be better off with a better gun for spraying topcoats. The technology has come a long way since the 502 days. I think they have a transfer efficiency of about 35% and the high pressure at the cap makes them more difficult to control than newer models.

The JGA-502 in my opinion is the best all around spray gun ever made. It is still an excellent gun for spraying synthetic enamel, acrylic enamel, lacquer and even basecoats (for base/clear painting). It does a relatively poor job of atomizing the newer acrylic urethane topcoat paints in single stage color and clearcoats. You can get a #9000 air cap for the old JGA's which that air cap was designed to handle the urethane topcoats. I have that setup and still use it relatively often for spot jobs etc. For full paints or large areas I use an HVLP gun with the clearcoats (iwata LPH400 LV, great gun). If you are serious about painting as a hobby etc then you need a gun that is designed specifically for spraying the newer urethane topcoat paints. I still like my old JGA but I have around 30 experience with that model of spray gun so I can pretty much make it do what it want out of it. An inexperienced painter doesn't have that experience knowledge database to work from, so their results in most cases would be less postive than the results I get of my old JGA. A #9000 air cap for your old JGA is going to cost you around $70. There are several lesser expensive spray guns ( in the $100 - $150 range) that are HVLP and are actually pretty decent guns. Not as good as the top of the line $500 spray guns but they get the job done. What all this boils down to is you're better off getting a gun designed to handle the urethane topcoats instead of trying to upgrade the old JGA then still have to learn to spray with that particular gun.

How I learned to paint.... Nursery school. This is going way back in time. Teacher gave us paint brushes and buckets of water. We went outside and painted a fence with water. Will test my old school [JGA-502] sprayer with water.

For safe keeping I put a manual here:

Please excuse my ignorance. I have NO spray experience. What pressure should air compressor be set at? My big one is 100 PSI and it is not adjustable. Got a smaller one 20 Gallon? With this one I can adjust the pressure.

Can I extend the Fluid Tip with a piece of threaded pipe? Will spray gun not shut off when I release the trigger?

I am hungry. Think I will open a can of soup. Hot soup GOOD :D
Undercoating Gun with 2 hoses and bottle
Item #20441