Michael, what do you want me to document -- that there are differences in chemistry?  From whence do differences in boiling point arise?  David has already stated that Chevron considers DOT 4 to be a replacement for 3.  I know that owner's manuals I have specify one, not the other.  I'll see what I can find stating that there are chemicals in one that are not in the other.  DMc

---- Michael Snow <slowmachine82@GMAIL.COM> wrote: 
> On Thu, Aug 19, 2010 at 4:21 PM, Dave Mcneely <mcneely4@cox.net> wrote:
> 
> >I may be wrong (never happened before ;-) ), but I think there are some incompatibilities in >materials, such that chemical interaction, or lube problems may occur whenever 4 is >substituted where 3 is specified or vice versa.  There are some differences in chemistry, >hence the different names.
> 
> Please cite any credible source (brake fluid manufacturer, DOT
> standard, etc.) to support this assertion.  This will live forever in
> the list archives and create confusion where there should be none.
> 
> -- 
> Michael Snow
> 1987 Syncro TiiCo
> 1982 Westfalia 1.9TD
> http://slowmachine82.blogspot.com/

--
David McNeely