even this guy ain't telling you the complete truth.

all liquid[also gaseous] hydrocarbon products are transmitted via pipelines. and they are all transmitted to the same terminals.

i care to tell you that the gasoline at a shell station is the same gasoline at a chevron station. principally because all of it was piped via the same line, to the same terminal.

the conventional wisdom is that once this benzine reaches the terminal, it is delivered to its customer[shell, chevron, et al] and it becomes transformed by the addition of their proprietary additive packages and octane enhancers.

hah!

it is all a con. imposed upon us by the gasoline sellers. do your own research. there is no octane difference from that labelled 87 at the pump from that labelled 93.

we are the most astounding bunch of cows imaginable. we believe what the oil companies tell us. how does it go? i love you. it's only a cold sore. etc etc.

ey so no joke, the times i fill up w 91 im wasting my money?

not sayn i dont believe you, just let me see some proof dawgie dawg **** dawgie dawg piss...

As has been pointed out in a couple of these posts. The gas comes into the tank farm and is distributed to various tankers from various companies with each companies additive package added at the truck. Because of federal control that keeps companies from advertising they have better gas, they all use whatever it takes to make the standard in the area the fuel is blended for.

Not only does the additive package change by what you buy, but the relative closeness the fuel ran in the pipeline to the diesel that preceded or the motor oil that follows also determines the price of the bulk.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Albert got most of it correct. I was trying to give the 50,000 foot view of gasoline, but there are a few things that still need to be clarified.

First, not all gasoline is transported via pipeline. Though it is safe to say that most of the gasoline goes via pipeline, a sizeable volume of product is moved via water. In fact, upwards of 25% of the total fuels volume is imported from mideast refineries.

Reacting to a "perceived" developing market in the mideast, most of the oil majors built refineries in places like Singapore and Saudi Arabia. To date, the market has not developed, so the finished product is shipped to America. Contrary to popular beliefs, gasoline is a commodity and, as such, behaves almost exactly as the classical supply/demand relationship taught in Economics 101.

Without getting on my soapbox for too long.......let me just say that anytime there is a spike in pricing, either universally or geographically, there is a hue and cry from the public that the oil companies have conspired to drive pricing up. This is usally followed with the formation of an investigatory committee to determine the cause of the pricing change. Since I am in the industry that undergoes these investigations, I can say with some certainty, that 99% of the outcomes from such investigations are that the pricing followed the classical supply and demand curves. End if soapbox, though I would be glad to provide more data if someone wishes.

The comments about product terminals was also partially accurate. Though all the major oils operate their own terminals, the capital cost of owning and maintaining a terminal in every market is prohibitive. To deal with this, gasoline suppliers negotiate "terminal agreements" with the various owners of terminals. As I originally stated in my first post, all gasoline is manufactured to the same national standards (ASTM) which allows you to co-mingle Exxon, Chevron, Texaco, etc in the same tank. The difference is the additive package. Simply put, if two companies share the same terminal tankage, they will each own and maintain their proprietary additization equipment at that terminal. So, when a Chevron driver fills his tanker, he tops it off with Chevron's additive from a Chevron owned tank maintained at that terminal. Since very little additive is actually added to any tanker batch, the additive is usually supplied, maintained, and discharged from 55 gallon drums. If a particular terminal moves a high volume, then the drums could be replaced with a small tank.

The last item I would like to comment on is the one with regards to octane. First off, octane DOES make a difference, if your engine is set up for it. Specifically, for any high compression engine, whether it be a new Mercedes, or an old American muscle car, more power can be produced with higher octane fuels. This statement becomes a little gray if your car is equipped with knock sensors, as are most of our Mercedes.

The optimum place to run any gasoline engine is right on the verge of knocking. That corresponds to the most thermally efficient place to operate; however, too much knocking leads to engine damage, while moving too much to the other side results in lost power and poorer economy. The knock sensors can determine the point at which the engine is just beginning to knock. The signal from the sensor is used in our modern engines to advance or retard engine timing to just keep you operating on the verge of knock, which is where you get the most power for the buck. Knock characteristics are affected by octane.

In reality, in most of our cars, you can drop a few octane numbers without being able to "perceive" a drop in performance since the ECU controls the spark advance. I DO run 89 octane, midgrade gasoline in my E320 and cannot tell the difference from 92 octane, because of the knock sensor control. Without the knock sensors, my engine would knock badly on the lower octane fuel.

Lastly, the octane specification is NOT controlled by ASTM standards; so, there can be legal issues around misrepresentation of actual octane. I can tell you, emphatically, that the major oils control octane to prevent such publicity.

Sorry, again, for the long post.

Excellent post!

To reiterate the salient points: Commercial gasolines for a given market are essentially the same. Octane rating of the various grades is one major difference and is carefully controlled. During a production run, a CFR (Combustion, Fuels Research) engine - a variable compression ratio research engine that has been around for over 60 years - continuously samples the finished product for octane rating. This is part of the quality control function.

The other difference is the additive package, but each additive package is blended to pass the same standard tests, so any attempt to say one is better than another is subjective, at best.

Guys continue to assert that Brand A is better than B because "my car runs better with A", but it's all in your head!

The final differentiation is price, which is what I use to choose brands. Whoever has the lowest local price gets my business. My cars range in age from 12 to 40 years, and I have never had any fuel system problems with any of them.

The final point is that "modern" high compression engines with a knock sensor(s) and electronic engine control can be successfully operated on regular grade fuel, even if the manufacturer recommends premium. Aggressive drivers might notice a slight drop in performance due to the less aggressive timing map, but the average driver is not likely to notice any difference in operating characteristics.

Duke

Nice post Duke. Though I run my E320 on midgrade, I have never tried going to regular unleaded; however, you indicated that you can't tell the difference. I may try a tank load just to answer the same question for myself. I would caution anyone from doing this if they have a high compression engine that does not have knock sensors in the engine management system.

I would generally agree with your philosophy of using price as a guide with a few caveats. Though the additives put into gasoline are "roughly" equivalent, there are some marketers who do not additize their gasoline. Keep in mind that additization is not mandated by law or standard.......it's strickly dictated by the need to provide some sort of perceived marketing "edge" in the performance of gasoline.

You'll potentially run into this scenario buying gas from, for example, a supermarket chain that has decided to sell gasoline as well. They do not own (nor want to own) any production facilities. They purchase their product across our truck racks on a "cash and carry" basis. Many of these companies will choose not to add additives. They MAY NOT even know about additization, since gasoline marketing is not their core business! As absurd as that sounds, you would be surprised to find how many independent gasoline marketers do not additize their products.

Then there is octane. Not controlled by law or standard. The small business owner can take the risk of cutting cornors on octane. Who's to know if he puts a load of unleaded regular in his premium tank? Afterall, who is going to sue the little guy? On the other hand, everyone wants to sue the majors!

Then there are a number of independents that are not in the gasoline production business, yet care about the marketing of their image. Since they care about image, they are more apt to additize and accurately list the octane of their products. And, they can market their product at a lower cost than the big guys. I would not have a problem buying product from one of these mid-tier companies.

Well, at least my posts on this topic are getting shorter!