Does brand of gas matter?

I see the best results from Shell V-Power. But if I cant get that, I uaually get Mobil Premuim, which is 99% of gas stations in the area, and is the cheapest Premuim gas here.

 

Northern California


My Ferrari doesnt care, but I have a Mustang that I tuned the computer myself, so it is kinda on the ragged edge.
I get the least audible detonation from Valero, and the worst from Chevron. If I put Chevron in , I literally can't floor it at low speeds.

 

I can only comment on Kalifornia gas. In the 1980's at the VW dealer we had lot's of problems with dirty injectors. After surveying dozens of customers we found that those who used Chevron had the least amount of problems. We also found that those who bought the new Fox bought the cheapest no name gas and had the most problems. Once we cleaned the injectors and got people switched to Chevron thier probems went away. A side benifit was that fuel mileage went up a few MPG.

I know the fuel from then is much different than we have now. In the 80's I had a European spec VW GTI engine in my Rabbit. It was a 1600cc with 10:1 compression and dual Mikuni Solex side drafts. It was a terror on Hwy 17. I took it to Baylands on Wed. nights for some fun. With the same weather conditions if I used any gas besides 92 octane Chevron it always ran a half second slower in the 1/4 mile.

Back in 1996 I learned that if I used Exxon in my 1955 Unimog it ran terrible. When I was driving a lot of back roads in the Sierra's it seemed like Exxon was the only brand available when I was in a remote area. Maybe the gas was old I don't know. There was not any evidence of water in it. With only 80HP in a 6500lb truck I also learned that it loved Mexican gas. With only 7:1 compression it was designed to run on what ever gas you could find in a war. The Mexican gas was not oxygenated so was 100% gas not 95% like we had in CA.

The only 24 valve BMW's that I have had to do valve jobs due to a burned valve used ARCO exclusivley. Carbon would build up on the seats and faces of the valves. Then they would not seal completely. Then the passing flame would cut a deep V notch in the valve.

A customer of mine has a Miata and gets newsletters from his Mazda specialist. In the summer of 2008 the Mazda shop had a sudden spike in valve jobs. He surveyed customers and with the high gas prices most of the valve failure customers had switched to Costco gas.

With OBDII and fuel trim I am finding codes set from dirty injectors flowing too much fuel. They don't seal in the closed position allowing more than the metered fuel to be delivered. I have found two scenario's usually cause this. Cheap gas or the car is not driven enough. I have seen this in Mercede's, BMW's and Ferrari's. It is really a big problem in the Ferrari's because they are not driven enough. From surverying customers I again have found those using Chevron have the least amount of problems.

The newest gimmick I have seen is Shell gas with nitrogen added. I have never liked Shell gas even in old carb cars. We already have 5% oxygenated fuel so taking away from the other 95% to put in nitrogen puzzles me. It is supposed to help keep carbon deposits down. Time will telll I guess. Would really need to do back to back fuel mileage runs and see if fuel trim changes any.

 

Yes, CA is very stringent now so there shouldn’t be an issue. I recall 20 yrs ago having to clean my in-line glass fuel filters one a month because of rust & particles, and determined the culprit to be the local mom & pop station.

If you assume that all refined fuel comes from the same supplier, and the only difference is in the additives which are added & mixed in route, and you assume that the station owners are legitimate (not adding x to the mix for example), then the only other variable is the tank & delivery system. This is an overly simplified example of course, and what it doesn’t take into consideration is that there are multiple suppliers of the base fuel. Determine where the non-additive base fuel is sold and you should see a correlation in performance/quality.

For me Chevron is the way to go. I've pulled apart a few MB V12's and the ones running Chevron were noticeably cleaner. As stated in a previous post, stay away from Costco. Even my Tahoe chokes on it.

 

Seattle

I tend to run on Chevron and Shell Premium in my LS, but make sure I stay away from the likes of AM/PM and Valero (can't say anything bad about them, just heard stories)
-Colin

 

OK, but:

Glad we're getting to a consensus here

I guess I'm gonna stick with Shell in the 360, but really wonder about it's "age" as compared to the quickie-mart mentioned above?......

This raises the question of "in car storage" - I wonder if the "high quality" additives used by Shell (etc) are of any benefit when the car is just sitting around? As many of them do..... Is it better to "store" the car (for a week or two?) empty or full? With or without additives?

Is there an AEH for fuel out there?.....

Cheers,
Ian

 

Regardless of vendor? Longest lines = Lowest price (generally). I like that parameter!

Cheers,
Ian

 

When you start tuning your own motors and reprogramming the fuel system & advance curve all bets are off.

I could probably make the argument that depending on the cam, timing, & compression ratio, fuel with a little water added could perform better at low RPM. Did I really say that? Yikes.

 

O2 sensors don't always like Chevron. Don't know why, but the techs have seen more than a few. Shell here if available.
That said, German stuff is fine with Chevron. Exxon quality here can be spotty, probably due to supplier.

 

I have read previously (here on Fchat, perhaps?), that regardless of what brand you're using, use it only for about 2K miles and switch to another brand for another 2K. Keep switching every 2K. The reason being that because the different companies have different additives, they don't "clean" everything. So, by switching it up regularly, you're covering the spectrum.

I've tried to consistently switch, but it's not always convenient unless you plan your fill-ups better than I do.

CW

 

This is worth reading, although I think it is about 10 years old. http://www.vettenet.org/octane.html

 

Evo, a fine British auto mag, did a careful test on just this subject a few years ago. They measured, if my memory serves, actual hp output, etc after fill-ups at various name brands, mom and pop stations and big-box stores. Their conclusion was that the over-riding consideration was fuel freshness. So I think the most important consideration is to use a gas from a station that has lots of business- which often is the cheaper station. I've been filling my cars on this basis for years and have never had an issue with Porsches, tuned Audis or the Ferrari.

 

That follows my thoughts as well. Most of the old steel underground tanks are a thing of the past...something that scared the tar out of me for many years after selling my gas station. Years later while working at World Ferrari, we shared a parking lot with a fairly busy filling station. They dug up their old steel tanks one day to replace them and just before the crane came in to do the swap there was a flash thunder storm. Filled the hole with water and floated that huge underground tank up until it broke the steel connecting lines and spilled some 600 gallons of remaining fuel in the hole. Sandy soil and all... they dug half way to Asia with the EPA standing their 24/7. Not too many of those old steel tanks left these days.

Alcohol is hygroscopic and absorbs water. Back in the early 80's when I owned the Phillips 66 I would close fuel sales for days after a delivery in the winter just so I could pump out the water from the bottom of the tanks. In the cold climate of Minnesota, condensation in the depots above ground tanks was a very serious issue. You could look at the huge storage tanks and see how full they were by seeing the frost layer on the outside...

With alcohol being part of the mixture now and it absorbing water...one only hopes the road to the station is a rough one to mix this all up. I cant speak for the current situation but the Amoco across the street got the same exact mixture of additives and gas as I did at the Phillips.... "Phillips 66 Specialty Blended Fuel" my as*.... Chevron got the same as we did back then. Leave the tanker driver a case of Cold Spring in a box on the tank covers on a Friday evening and I would get a few hundred extra gallons and Amoco was sort the same amount. That old wooden tank dip stick wasnt as accurate as the analog meter on the truck. Im sure things have changed for the better since then.

 

The automatic systems have made life better for a gas station owner.

http://www.opwfms.com/ProductsTankGauges/sitesentinelisite/index.html

As for water in the fuel I have seen a lot more vehicles that are in for water in the fuel as of late than I have over the past 20 years of twisting wrenches. About the only other time I saw more. Was when I worked on Polaris watercraft and there filler necks and caps kept breaking allowing tons of water to enter the fuel system.