Back in the late 70's early 80's I worked for the company that made Castrol's DOT 4 LMA fluid.
Here's a couple references that I could find quickly:
http://www.hotrodheaven.com/tech/brakes/brakes8.htm
http://www.xs11.com/tips/maintenance/maint1.shtml
http://www.bestbrakes.com/brake_fluid.shtml


Harold Wilson
41 Chevy 3/4 Ton