[AT] stiff tractor day

[ROBBRUT at aol.com]

Mike-
 
You probably already know that commercial hydraulic fluids contain  additives.
 
Some are emulsifiers specifically designed to permit water vapor  which has 
condensed and gotten into the fluid to stay in suspension and not  readily 
settle out (to the bottom of whatever it is in), then freeze/expand and  break 
whatever it is in.
 
The petroleum engineers I have talked to say that the theory is that  
although ice still forms, the crystals are small and diffused so that they are  
surrounded by a "cushion" of oil and can expand without damage.
 
I have not tried it yet, but the consensus was that the same trick (adding  
some alcohol) which acts as "Drygas" would permit the oil, water and alcohol to 
 combine, and not remain separated but suspended, as the emulsifiers do.
 
By the way, since the oil lasts much longer than the additive's  
emulsification ability does, it's also possible to add some emulsifier to gain  back the 
protection the new stuff had.
 
-Bruce Thompson