Ridgeback_Pilot

Since acquiring my 2000 M5, I've been wondering what folks believe is the best brand of U.S. gasoline for the Beast?

Here in California, all we can get is 91 octane but we do have a choice of Chevron, Shell, Union 76, Exxon, and the lesser known brands (e.g., Valero, etc). I've been using Chevron primarily, and Union 76 as well. Is one better than the other, or are they all pretty much the same?

Of course, I'm sorely tempted to put 100 octane aviation fuel in my car, but I've held off so far since avgas is still leaded!

Does anyone have a preference for gasolines, and if so, why?

Thanks, Mike

__________________
1986 E24 635CSi "Shark"
2004 Volvo XC70
2000 Ford F150
1981 Cessna Turbo Centurion
2000 Dinan M5 Carbon Black/Caramel (Sold)

buymenow00

I use Chevron Supreme myself and am pretty happy with it. My mechanic actually prefers Chevron also...

Nice color scheme BTW...carbon blk over caramel...

__________________
2011.5 M3 Sedan ZCP

Retired:
2005 330i ZHP
2007 M Coupe
2003 M5
2001 530i/6
1992 325i
1981 320iS

atlantisvip

I personally stick to 76 and Chevron.. Being a NASCAR fan, I try to use to 76

One of the nice things here in Dubai is that for about $20 I get a full tank of 98 octane..

buymenow00

NASCAR...Dubai?? Interesting...

atlantisvip

I'm from San Diego..

Wake Champ

If there is one thing I know, stay away from arco and 76. Circle K gas is garbage! I think the best bet out west is Texaco (if you can find it) mobil1, or chevron(which is good but overcharges) . 91 octane or higher of course

pkarmouche

Good thread.

Chevron for me.

I have two "first hand experience" stories. Before you read on, I'm no expert and am only speaking from what I've been told or read - and are "impressions" on the subject. These experiences though do back up my impressions:

Story 1:

My first "brand new" car was a 1988 Chevy Z24 with a 2.8l V6 and Bosch "multi-port fuel injection". (Side note: it also sported a Getrag 5 speed which had a feel almost identical to my M5). I had a buddy who owned one of the same cars, but an '89 model with the same engine/tranny. We both observed the same behavior:

When using Chevron or 76 the car would run great. Smooth idle, smooth strong power, etc.

When using Arco, Shell or a "no-name" brand we would get a rough idle, and the engine would stall a lot. It was very frustrating and the change was instant, fill the tank with some tasty Techron and it was back to a perfectly running engine.

Story 2:

A friend of mine does his classic car restorations and engine rebuilds. He had a Chevelle SS ('71?) that he ran the motor almost 100,000 miles since "factory new" exclusively on Premium Shell. He tore the engine down to rebuild it and found all sorts of grimey, gummy build up. He doesn't prefer Shell anymore.

I later learned that Chevron and 76, for two examples, use a SOLVENT type additive. Shell (and most "off brands" use a DETERGENT type additive which is considered harder on certain engine components and can "build-up".

I did some research a few years back:

After listening to a talk radio show that spoke about this subject, I asked a couple of fuel truck drivers about where they fill their trucks. I also read up on the Internet. What I learned is that the "Big Brands" refine their own fuel. "Off Brands" like Rotton Robbies, Tower Gas, etc. use whatever brand or refinery offering the best deal (but they don't change very often). Ask a driver unloading fuel at a Chevron station in the SF Bay Area and he will tell you he got his load from the Chevron refinery in the East Bay. Ask a driver unloading fuel at a Citgo and he'll tell you he got his fuel from XYZ refinery - where they gave him a load treated with an additive selected by Citgo. Other days he might take a load from the same refinery to "Al's service station" (with an unknown additive type).

See, the big brands may have differences in the way the fuel is refined, and some brands' fuel may be "cleaner" than others. Smaller brands and "discount" brands (like Arco) may even all come from the same source - BUT - have different additives.

Anyway, one day I hope to run into someone who is an expert on this subject.

Paul

P.S.- funny how anal we are about the fuel and oil type we put in our cars and how it can affect its "health". Wish I had the same regard for myself - sheesh those hotdogs and pizza for lunch can't be good for my Vanos Oh and what's my blood type again? A+5w30?

paule

I use Sunoco GT Premium (http://www.racegas.com/fuelspecs/default.asp). I get it delivered in 55 gallon drums and for like $4.46/gallon. I notice a dramatic difference in performance (although my wife thinks it is psychological) and I tried (in a somewhat scientific manner) all the stuff available at the pumps. Although I can't tell the difference between the GT100, so I will probably switch to that as soon as I am finished with my last 110 gallon batch.

On the 104 octane, I dropped my 1/4 mile time .5 seconds, although my wife disputes the causal relationship between my time improvement and my use of race gas .
Paul

__________________
2002 Sterling Gray (Dinan S2) - SOLD!
2006 E60 M5 Saphire Black/Perforated Full Sepang Leather/Madeira (Week 40 Production)

paule

For what it's worth, a while back, I tried to figure out what exactly the octane rating on gas meant because I wanted to understand how and why paying $5/gallon would benefit me.

To summarize, the higher octane fuel is less volatile, and so will endure higher pressure/heat before spontaneously igniting (which is what you don't want it to do in your cylinder).

ASTM has two different tests which pits the sample fuel against reference fuels and the references fuels whose knock intensity (and corresponding octane number) is closest to the sample determines the octane number of the sample.

The two tests are the Motor test (http://www.astm.org/cgi-bin/SoftCart...120+1107790549) and the Research test (http://www.astm.org/cgi-bin/SoftCart...120+1107791040) and the octane rating that shows up on the pumps is an average between the two (hence the R+M/2 you see on the pump).

I think the research test runs the test motor at 600 RPM, and the motor test runs it at 900 RPM.

With respect to the additives that different companies add to their blend to reduce deposits and give other benefits, I couldn't find any comprehensive/uniform unbiased research comparing blends.

An interesting article on relationship between crude oil, propane, our unleaded gas and diesel is http://auto.howstuffworks.com/question105.htm. Anyone with a high school chemistry background can understand why diesel engines get better mileage than gas.



Paul

FAST 5

In my area, one can purchase Sunoco 94 at the price
of $3.15 gallon. It's the best choice for our motor's.