On May 15, 7:31 am, dpb wrote:
On May 14, 3:04 pm, mm wrote:
Found almost nothing about Type A transmission fluid on the net,
....
OK, I had found a couple of other things that I meant to add (and I
promise this is the last
)...I looked at the SAE site on standards
for ATF and found two abstracts that had some interesting info..
First is abstract from a technical paper "History of Automotive
Lubrication" --
Today's lubricant quality is defined by classifications, or
specifications, that are established by taking into account
metallurgy, equipment design, and/or operating conditions. For engine
oils, the American Petroleum Institute (API), the Society of
Automotive Engineers (SAE), and the American Society for Testing and
Materials (ASTM) are the key bodies that define industry needs,
establish classifications, and develop test methods to assure that
lubricants meet the required performance. For gear oils, API and the
Coordinating Research Council (CRC) play a similar role. The U.S.
Military and original equipment manufacturers (OEMs) have their own
performance requirements that are usually over and above those of the
API/SAE/ASTM and API/CRC. The performance requirements of automatic
transmission fluids (ATFs) are established by OEMs, such as General
Motors Corporation (GM) and the Ford Motor Company. ...
The second was a paper written by GM engineers for some conference in
1968 which was for the dual purpose of getting the info out and
promoting the (then new) product --
Title: Dexron Automatic Transmission Fluids Are Higher Quality Than
Formerly Used Type A Fluids
Author(s):
Robert L. Anderson - General Motors Res. Labs.
Norman A. Hunstad - General Motors Res. Labs.
Abstract:
The minimum quality of Dexron automatic transmission fluids is higher
than that of the formerly used Type A fluids. They will provide
improved transmission operation, both initially and for extended
periods of service.
These fluids were developed principally to achieve longer shift-time
retention and clutch plate durability. Advances were also made in
respect to low-temperature fluidity, antifoam quality, fluid-seal
compatibility, oxidation resistance, and fluid-nylon compatibility.
This paper reviews the development of these fluids, and outlines the
recently established specification requirements and qualification
procedures which are used to define this higher quality level for
fluids supplied to the service fluid market.
I'm sure a search for Ford and Chrysler would produce similar
reports...
So, overall, it is a case of the manufacturers developed products
specifically designed for their own needs.