Gregg Carlen wrote:

Blain,
Does it really matter if its DOT3 or 4?  I have 3 in my van and haven't
noticed anything wrong.  Should I be using DOT4?  How come?  :-)

     This has generated a lot of traffic.  I need to apologize somewhat for
     perhaps promulgating another Internet "apocryphal" tale.  A few weeks
     ago there was some traffic on the Vanagon list about DOT 4 being the
     required brake fluid; since there wasn't much discussion at the time,
     I took it as the gospel.  The service guy at the local non-dealer VW
     repair also concurred.

     Turns out that the owners manual (which I didn't have at the time) and
     the Bentley book (which I did have) both indicate that DOT3 or DOT 4
     may be used.  Some listies agreed that the additional resilience of
     the DOT 4 was worth having.

     Meanwhile, I changed mine out (it needed it) and "installed" Castrol
     DOT 4.  Bleeding the system was a gold-plated b*tch, and it's still
     not 100%.  I was getting air out of the back brakes long after I
     expected (pretty much ran an entire quart through it).  I'm beginning
     to suspect that the piston for the rear circuit is drawing air and
     that it may be time for a new master cylinder.  Who was selling these
     for $100?

     BTW, can anyone explain the Bentley instruction to "flip the lever on
     the pressure regulator towards the rear of the car" before bleeding?
     And why does it never instruct you to "flip it back"?  Does this even
     apply to the '91?

     TIA

     -Blaine Bachman
     Albuquerque