[200q20v] Pentosin

Phil Rose pjrose at frontiernet.net
Wed Feb 7 18:31:54 EST 2001

>Fellow listers:
>Following up on a somewhat distant thread.......I recently picked up several
>containers of synthetic Pentosin 11S from Parts Connection (on sale -- $12 a
>container!) and remembered that I'm still running the old nonsynth stuff.
>Warnings on both containers proclaim boldly (Achtung!!!) not to mix the two,
>but I seem to recall info from Scott's website that mixing the two was
>acceptable (though I recall his preference for 11S).  Do I need to flush the
>system and fill with 11S if I start to run low or can I top off/mix old with
>the new stuff?  Does it matter?

The older (pre-1989) Audis had been using Pentosin 7, but they began 
to be "fed" Pentosin 11S by dealers after '89, since that is said to 
have been the _only_ Pentosin available at AoA dealers for the last 
decade. So, we all surmise that Audi believes the 11S fluid is 
"backwards compatible" with respect to systems using Pentosin 
7--presumably without the need to drain/flush. If you buy that 
reasoning (and would Audi ever do anything harmful to your car?) it 
ought to be OK to start topping up with the 11S.  For reasons we 
don't exactly understand, it's presumably _not_ recommended to mix 
the 7 into a sytem that is nominally 11S. The reason for that might 
be as simple as recognizing that 11S can operate over a wider 
temperature range than 7, so no one should want to "degrade" the 
(low-temp?) temperature characteristics of their 11S system by adding 
any 7.  As I see it, these various mixing scenarios are not likely to 
be catastrophic or seriously harmful. But be sure to tell us if it 
is. ;-)

Heck, at "only" $12/L, it wouldn't hurt to drain all that dirty old 
fluid, and get a fresh start--especially if what's in there right now 
is mainly Pentosin 7.  Be sure to try and clean out the reservoir's 
filter screen if you do that.

If you change fluid now, you can blame any future problems on the new 
11S. If you don't change, you can blame it on the 7.

Phil Rose
Rochester, NY
mailto:pjrose at frontiernet.net

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