[TowerTalk] WD-40

[Howard Hoyt]

AB2ZY said:

>>"...I was wondering what the "magic ingredient" in ATF was that busted rust..."

The factors contributing to ATF's penetrating and antioxidative performance is due to the additive package, which makes up up 15% of ATF by volume.  Consider that in an AT, there are clutches which must not slip excessively, and yet they are bathed in ATF.  This characteristic is achieved by a stout surface-tension friction modifier package.  The anti-oxidative package is designed to keep the many aluminum and steel parts in close proximity from forming dimetallic corrosion cells.  In addition there are detergent and anti-wear packages which contains molecules structured as micelles, one end which is oliophilic and the other end is hydrophilic.  These molecules have a high affinity for metal surfaces while remaining suspended in the oil base.

Bottom line: ATF is highly attracted to metal, has corrosion neutralizers and very low surface tension, and the addition of acetone as a solvent base to lower the viscosity greatly assists the penetration of this soup into cracks and crevices.  Once it is there is neutralizes corrosion to a small extent, but also deposits anti-wear agents which help coat asperities with a film which assists release of the frictional interface.

We have seen similar results from small amounts (~5%) ZDDP dissolved in acetone, but I believe the friction modifier in ATF really boosts the wetting and performance in this application.


Howie - WA4PSC

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Howard Hoyt -STLE/SAE/STC
Dir. of Engineering
ZPlus, LLC
www.zddplus.com