Re: What Gas to use?

[Michael Murphy <mmurphy@nais.com>]

Greg Wolters wrote:
> 
> Hi Listers...
> 
> What is your opinion on the octane rating to use for US Audi's?  My
> manual sez min 91 RON, but I have also heard that this isn't true.  Is
> the Audi manual using the same rating method as US gas companies?
> 
> I have heard that as long as you aren't getting any knocking, the lower
> octanes are fine and there won't be any damage to the engine and you can
> save some money.
> 
> Thanks in advance!

Greg,
The US measures octane ratings by (R+M)/2 or
(Research Octane # + Motor Octane #)/2 
(R+M)/2 is aka AntiKnock Index (AKI).

Audi recommends 91 (R+M)/2 (95RON) for max. engine performance, but also
states minimum octanes of 87 (R+M)/2 (91RON) can be used.  The inside of
your gas filler cover should have a sticker with info for your
particular model.

Havin a 100 w/NF engine, I can attest that use of fuel below 92 (R+M)/2
makes for poorer performance.  And there's even some differences in
performance between 92-93 fuels.

More than you would ever want to know about Auto and AvGas fuel can be
found at:
http://www.geocities.com/CapeCanaveral/Hangar/7082/f_gasoli.html
HTH,
MJ Murphy