I've been rustproofing cars for over 20 years. I made a hobby out of it. I even picked the brains of corrosion engineers when I was working at Chrysler who recommended Texaco Rustproofing compound.

I tried oil... didn't like it... it disappeared, leaving the metal dry before winter was over.

The Texaco rustproofing compound is used by only a few rustproofing shops in the Detroit area. When I was a young engineer, I went on a quest for the best rustproofing compound in the Detroit area. I sat down with some people that manufacture Polyoleum, and found I wasn't too impressed with their product. Though it sprays on wet, it hardens to a wax consistency, which can get harder with age, delaminate and even trap contaminants, leading to poultice corrosion.

Type L Texaco rustproofing compound is essentially wool grease with 1 to 3% stearic acid. There are other formulations of this compound such as for painted surfaces, but I use Type L, formulated for undercarriage.

The compound must be cut with mineral spirits to be sprayable. The mineral spirits evaporate leaving the greasy compound on the sprayed surfaces. This coating must be renewed every few years since, with time, the compound dries away to nothing, especially in the high-wash areas. This is no big deal, since I have yet to see rustproofing from a shop last for the life of the car without touchups. (To everyone in Chicago, how may old cars have you seen with a "Rusty Jones" sticker that look like hell?) I buy the compound from a wholesaler in Detroit in 5-gal pail or 1/4-keg quantities. The pail can last me at least 3 jobs; and I like to spray it on thick!

I've adapted my paint spray gun with a long nozzle made of brake tubing to pressure spray the compound into seams, crevices, and blind areas where corrosion typically starts. Corrosion rarely begins in the middle of a metal panel! The compound needs to be reapplied every few years, especially in the high wash areas. But I've never had rust on the protected parts. The only rust I've had is where it originated from the outside or in the A- or B-pillars, which are closed sections.

I've had mechanics praise my work during buyer inspection. Nothing like rustproofing a car yourself for a job done well.

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95 E320 Cabriolet, 159K