[AT] 90wt oil and fords

[Larry & Barb Dotson]

chuck/walt
Copper alloys are generally referred to as "Red Metal" due to the color of
Copper. Brass has Zinc and Tin in varing amounts. Tin changes the color to
yellow when using a realitively high percentage. Bronze is Copper with Tin
and Lead. Again as the percentage of Tin increases, so does the yellow
color. Most bushings found in older tractors are either Babbitt or Bronze.
The Lead in Bronze does not alloy with the Copper but is found in seperate
individual pockets. Lead is very easily corroded while Tin is very resistant
to corrosion. Lead is natures best bearing material for sleeve type
bearings. It is soft and lubricating as a bearing, but has several
weaknesses. It is very weak and requires Tin to help with the corrosion.
Lead is also poisoness and is therefore being eleminated in most automotive
engines and transmissions. Having said the above, I believe it is the Lead
in the Bronze bushings that would be the most likely to be attached by some
oil types.

Larry Dotson
Copper/Lead specialist
Clevite engine bearings/bushings (retired)