Which gas should I use?

[Aleksander Mierzwa <alex@matrix.com.pl>]

Hello List!

The owner's manual for my 5KT says I should use 92 octane gas. I
understand that this is US AKI octane number, so it is calculated using
(research+motor)/2 formula. The gas pumps here in Europe are labeled by
research octane number. I was using 95 octane gas until someone on this
list (Alex, as far as I remember) posted the conversion charts for
research and motor octane numbers and I realised 95 RON is equivalent to
only 90 AKI, so it seems that I was using wrong gas. I started to use 98
octane gas, the problem is, it's not widely available here in Poland and
the only gas stations that always have it are those belonging to the
Finnish oil corporation Neste. They import 98 octane gas directly from
Finland and they advertize it as "the first reformulated gasoline in
Europe". I know that reformulated fuels are being already used for many
years in USA and I heard very bad things about them on this list. I
didn't notice any improvement in performance or gas mileage using 98
octane fuel, but I think the fuel pump is a little bit quieter (maybe
this stuff has better lubricating capabilities?). So, what in your
opinion should I do?
1) Use reformulated, "super clean, increases power, prolong catalytic
converter life" etc. etc. 98 octane gas
2) Trust my knock sensor and use good old 95 octane gas (which is much
cheaper, BTW)
3) Find a gas station that sells non-reformulated 98 octane gas? (may be
difficult, though)
Thanks for any opinions.

Aleksander Mierzwa
Warsaw, Poland
mailto:alex@matrix.com.pl
87 Audi 5000CS turbo (mine)
88 Renault Medallion wagon (mom's)
91 mountain bike (just in case both cars broke at the same time :-)