Re:Pentosin

["Gary Barry" <Gary.Barry@trw.com>]

Four years ago, the mechanic who services our family Audis replaced the
rack and re-sealed the pump in my 86 5000CST.  He refilled the system
with synthetic Pentosin (red cap) without flushing the system.  As of
today, the rack and pump work fine and have no leaks.  The mechanic says
he uses synthetic Pentosin regularly where Pentosin is needed and has
had no problems.  I have no idea what the difference in characteristics
is between the two types as far as impact on the hydraulic system and
temperature extremes, although it does get hot here in So. Calif.

I have never had to add any Pentosin to our 92 100CSQ or the 90 90, so
they have the original green-top stuff, which itself is still green in
the reservoir.  I probably would not top off with synthetic on these
cars since I have a full bottle of the green-top on hand and would not
consider switching without at least draining the old.  Reason?  I need
to find out if the mechanic tops off with synthetic or only uses it for
replacement purposes when the system is drained.

Gary Barry