pentosin issues

[Mark Trank]

Forgive me if this is a well-worn thread, but in the last day or so my 200q
has been leaking pentosin.  The car was not used for about 2 weeks while I
was away on vacation.  I have been using the synthetic variety (11S?) for
some time, rather than the other type (7?)  Each can has a prominent warning
about not mixing the two.  I've got a full liter of the non-synth stuff that
I would like to use to maintain fluid level in the reservoir while I
diagnose the problem.  Are the warnings to be taken seriously or is mixing
the two innocuous?  Has anyone purchased any lately, and gotten a good
price?  I stocked up a few years back when Blau (I think) had them on sale
for about $11 a liter.  Now I'm down to a half-liter of the synth and a full
liter of the non-synth, left over from my 100q and 5000q.  Personally, I've
never really understood the difference between the two types of pentosin
anyway.

Thanks.  Feel free to reply off-list.

Mark
91 200q20v 104k miles