Checker Motors Corp M-10M-8 is a very interesting brochure that leaves it’s readers today with one major question.  But before we ponder that single question let’s recap the brochure.  The brochure is titled “Now! Checker Puts Proof Into Rust Proofing”.

According to the brochure rust is the most serious problem confronting automobile manufacturers.  It further explains that each Checker has a zinc chromate red oxide primer covering the body.  All detachable parts would also be treated with a “thermos plastic sealer” to protect the Checker from rust. To complete the rust proofing procedures, Checker would apply Texaco Compound L to pillars, the lower sections of all doors, trunk and to the space below the rear quarter windows.

A well knowned product, Compound L was originally developed for industrial and railway applications. Back in the late ’50s or early 60’s a Sales Engineer in New Orleans tested it at a Texaco sulfur processing facility and found it to be outstanding at guarding againstt rust.

The Type L Texaco rustproofing compound is essentially wool grease with 1 to 3% stearic acid. Fatty wool grease is a fatty, pale yellow wax that coats the fibers of sheep’s wool and yields lanolin, also called wool fat.  The acid provides a mild etch of the substrate for better adhesion. There are other formulations of this compound such as for painted surfaces.

Today on the according to Chevron Texaco,  Compound L provides the following advantages in protection with multiple applications.

  • Excellent long-term rust protection — Petrolatum and special additive system form a non-hardening, self sealing film to protect surfaces against the elements. Good water displacing capabilities ensures that the protective film is also waterproof. The special rust inhibitor system ensures maximum protection against corrosive attack. Good penetrating characteristics ensure difficult-to-reach seams and crevices receive effective corrosion protection.
  • Minimum surface preparation required — Ability to penetrate existing flaky or heavy rust means that little or no preliminary cleaning of metal surfaces is required before application. This penetrating ability makes existing rust easier to remove, should it be considered desirable to do so for a better or more economical job.
  • Minimal cost — Self-sealing properties of the protective film minimizes the need for touch-ups when film damage occurs through scratches or brush marks. The overall cost of this soft film rust protection is much less than ordinary paint.
  • Easy removal — Soft protective film is readily soluble in petroleum solvent or kerosine to enable easy removal when required.

According to Checker’s Graphic Illustration Sheet No. 264 titled Rust Proofing – Aerobus (TEXACO) dated October 1st 1965, the application of Texaco Compound L was extremely liberal. The engineering illustration,  instructions from engineering to the assembly team,  adds additional application areas beyond what is described in the brochure.  The instructions called for application for quarter panels, fenders, drip rails, body seams and body fenders wells.

Within the complete set of Checker engineering illustration guides the Texaco Compound L instructions can be found that cover a span of 1965-1975.  Given the liberal use of the Texaco product the big question is:  why didn’t it work?

Anybody who owns a Checker is well aware of the significant rust issues found in Checkers.  Checker owners typically are in a constant battle trying to prevent rust on their prized machines.

The answer to the question appears to be that rustproofing is not a “one and you’re done” deal. The coating has to be reapplied, typically on a yearly basis, to ensure that the car remains resilient under harsh weather effects stemming from moisture, not to mention the dirt and debris that gets lodged in its various crevices.  As a Checker ages, the effectiveness of the factory rustproofing will diminish,  unless the Checker was regularly re-rustproofed the longterm effects of rust will ultimately destroy the Checker.

Bill Beurken’s photo of his Aerobus 15 display typical Checker rust

Texaco Compound L is still available today and we have no doubt that is it a great product. For more information here one link to the product.

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