Date:         Mon, 12 Jul 2004 13:22:56 -0800
Reply-To:     Mark Tuovinen <mst@AK.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Mark Tuovinen <mst@AK.NET>
Subject:      Re: Fuel Octane, Additives
Content-type: text/plain; charset=us-ascii

To my knowledge if your vehicle calls for 87 octane fuel you will not benefit from higher octane fuel, but if you use 87 octane fuel in a vehicle that calls for 91, you will see a difference.

My response is based on two things, personal observations of my Audi, and a science fair experiment that my son used to win his age division in a statewide contest several years ago.

My Audi calls for 91 octane fuel and I have observed over several years and varying weather/driving conditions that it does indeed get improved mileage and run better with 91 octane vs 87. Enough so to easily justify the higher fuel cost, the mileage difference alone more then covers the cost variance.

For his science experiment my son wanted to compare CO emissions from an automobile using different grades of fuel. We took a vehicle that calls for high octane fuel and ran I/M tests on it using 87, 89, and 91 octane fuels. The engine burned much cleaner with the higher octane fuel, and ran better too. In fact the 91 octane fuel burned so much better that it increased the idle speed and we had to readjust it. The differences were probably more noticable on the car we used then most people would see as it called for a minimum of 99 octane.

Mark in AK

----- Original Message -----
From: Russell Patten <toolvanagon@HOTMAIL.COM>
Date: Monday, July 12, 2004 7:00 am
Subject: Fuel Octane, Additives

>   Lets start a thread on fuel octane, and oil additives.
>
>   My girlfriend and I are in a constant argumentative-type
> discussion about
> whether it is worth the extra 10-20 cents per gallon to use 93
> octane fuel.
> I am a proponent of using premium grade fuel.
> I belive that it is cleaner and more refined, and that the octane
> increasesfuel economy, performance, and lowers the operating
> temperature of the
> vehical.  I have seen evidence in a Mazda MX6 V-6 that I drove
> that it does
> indeed decrease operating temperature.   (That car ended up
> shooting coolant
> out the tailpipe anyway, replace your thermostat)
>
>   If I fill up my tank once per week I calculated the addiitional
> cost of
> high-octane fuel is approximately $102 per year, which, in the
> long run, is
> chump change compared the the cost of other repairs, upgrades, and
> modifications I will most certainly perform on my van.  If it actually
> increases my gas-mileage it should save me money, theoretically.
>
> My girly says, "If the car runs, the gas is good"    hrm....
>