Date:         Thu, 26 Aug 1999 09:30:52 -0400
Reply-To:     David Beierl <dbeierl@IBM.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@IBM.NET>
Subject:      Re: Octane requirements
Comments: To: James Ruch <jpeterruch@HOTMAIL.COM>
In-Reply-To:  <19990826125807.16144.qmail@hotmail.com>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 05:58 8/26/99 -0700, you wrote:
>Hey... have I been paying extra bucks for the 91 octane I'm put in my
>"snugvagon" for no good reason?  Is there any reason that I should not fill
>up with regular?

Hi James -- There are three things that distinguish super from regular: 1)
higher knock-resistance, 2) higher detergent levels, usually, 3) *less*
energy per gallon.

If your beast is specified to run on regular -- my '84 is -- and does so
without knocking, attribute 1 won't do you any good.  The increased
detergent, though, may help keep your fuel injectors clean, which is a
win.  However, I believe that as FI cars have become commonplace the
detergent levels of regular have been generally increased to match
premium.  There was a lot of fuss about this 5-10 (?) years ago, but
haven't heard much lately.  If the price difference is 25 cents, then 25
gallons would equal the price of a bottle of Techron -- but you only use
Techron every few thousand miles, so I don't think there's an advantage
there.  Assuming, of course, that premium gas would make the Techron
redundant, which isn't clear to me one way or the other.

By messing with the timing you might gain a performance advantage with
premium, although surely nowhere near the difference in price.

Cars with knock sensors (which Digifant does not have -- I think Digifant
II may) can be adjusted to run optimally with premium but retard timing as
necessary to run on regular.  I don't know what tradeoffs there are, but
this might be the best of both worlds.

david
David Beierl - Providence, RI
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"