Re: quattro-digest V3 #664

[shields@tembel.org (Michael Shields)]

> Is using 89 octane okay with the A4Q? I get similarly bad mileage with my
> auto tran A4Q. (15-20mpg). Maybe I can at least switch to 89 octane from 92 to
> save some money. I think the documentation for gas requirement is conflicting.
> The fuel door stick says 92, but the user manual I thought says something else.

There are two ways to measure the octane -- the Researh Octane Number
and the Motor Octane Number.  They are indexes of the same property under
different conditions.  Audi likes to specify a gas in terms of the RON,
but what you see on the pump sticker in the US is actually an average of
the RON and the (lower) MON; that's why the fine print on the sticker
will say "(RON+MON)/2 method".  The usual "87 octane" gas will have an
RON of 91.

I don't know why Audi gives the RON; maybe that's how pumps are marked
in Germany.

http://www.ca.sandia.gov/carnival/engine.dir/html/gas.html will tell you
more than you wanted to know about this.  Section 6 talks about octane.

Does anyone know when Audi started adding knock sensors?  I don't think my
'86 CGT (KE-Jetronic CIS) has one, which is a shame because it means I
don't have the option of paying a bit more for the good gas and getting
any benefit from it.
-- 
Shields.