Brand of Gas and MPG

what about sam's club gas.....any info on that gas

 

I know that Wal-mart/Sams happen to buy from whichever is cheapest when they order, and they have a much higher complaints of bad gas/water in the gas. This is secondhand knowledge from knowing someone who works at Home office manning the complaint line on the TLE/fuel hotline.


Also I remember an article a few years ago about where gas stations get their gas from. I can not vouch for the validity of this article Boycott Foreign Oil - BreakTheChain.org but of those on the list I prefer Conoco. Shell and Texico have the best quality of gas I have ever used, but past issues with those companies along with them being on the list causes me to not stop there unless I have no other convenient choice.

The biggest thing that will cause me to never go to a gas station is them charging $0.10 more per gallon for using a debit card. These are some of the most powerful companies in the world (Exxon etc..) and they can not negotiate with Visa/Mastercard to reduce the 3% charge??

 

I'm sorry, but this notion is incorrect.

 

I've long suspected there are regional differences based upon the feedstock:

• Upper midwest - Canadian
• NorthEast - middle eastern
• Dixie and lower midwest - Gulf, Mexico, and S. America
• High plains - Wyoming
• West Coast - California, Mexico and Alaskian

Each region has their own sets of refineries but they are fed by different feedstocks. Although refinery principles are well known, I suspect they at best are shifting crude oil stocks into gasoline using whatever is their most cost-effective approach based upon the feedstock. Organic chemistry, as much art as science.

Bob Wilson

 

here in Seaside Oregon and the rest of Oregon all gas is 10% Ethanol.

Just got back from a trip to Portland Airport and got 53.2 MPG.
calculated.

The gas I used was the least expensive in Seaside, no name brand.

So there you go.

alfon

 

amazing how many people are attached to 'their' brand of gas. i hear a lot of theories and rumor, but not much fact. we live in a one horse town with one gas station (mobil) and a nice mechanic, one small grocery store, one coffee shop and one package store. (thank goodness) we try to support them so we won't lose them, so, it's mobil for us unless we're on the road, then, it's whatever we can find.

 

I'm in the oil business, so let me see if I can explain this.

In the old days, refiners also owned gas stations. They refined the oil (usually their own oil) and shipped it to the stations for sale. That was a long time ago (pre WWII).

Today, refiners produce gasoline and put it in pipelines. The pipelines empty out into terminals all over the country. It's mostly a big grid, gasoline from a Shell refinery might end up in an Exxon terminal. There are exceptions. Some regions have short pipelines connecting them to only one cluster of refineries. The best example is northern California / western Nevada. Their pipeline runs only to the bay area refineries.

Pipeline companies set the specs for themselves and for government rules, and there are over 100 due to state/regional standards for gasoline. It's a real mess and it adds alot of cost, but noone seems to care enough to nationalize the fuel specs.

All the terminal does is inject the detergent additive for that retailer, and add ethanol, if required.

Refineries themselves also usually have terminals for serving the local market. If there's a refinery within about 50-100 miles or so, chances are you are buying gasoline from that refinery, no matter what brand is on the station. The brand only affects the additive they put in.

If there is no nearby refinery, you're getting anyone's gasoline, but it will still have that brand's additive. And where the gasoline actually came from can change week-to-week as the terminal refills their tanks from the pipeline.

Retailing is really a separate business. For example, if you don't like ConocoPhillips, they got out of the retail business. COP doesn't own any retail stations except one...the one right by their corporate HQ in Houston. All the rest of the Conoco and Phillips66 stations are independently owned. If you go somewhere else for gasoline, you could still be getting ConocoPhillips-refined gasoline. Same for all the rest. So if you avoid one station, you're really only hurting the guy who owns that station.

There are other factors though. Fuel pumps at the stations do have filters. Does the station owner change them? Does the station owner actually buy the branded fuel with the additive. In principle, they could buy any gasoline, or any hydrocarbon mixture for that matter, and put it in the tanks to sell as major-brand fuel. Yes this happens. So, if the station is ratty, or the owner looks shifty, they might be playing these games. The majors can and do pull branding if they catch stations doing this.

If one day it's a Shell station, then the next there are no signs and you can see the light bulbs behind where the Shell logo was..then the next week he's a zippy mart still selling gas, chances are Shell pulled his branding. I'd stay away from a guy like that.

A note about octane numbers...Octane is a measure of resistance detonation...that's it. High octane lets the manufacturer increase the compression ratio. That's where the benefit comes from. If your car has a lower CR, and is tuned for 87, then any higher than that will be a waste of money. It detonates/preignites or it doesn't. There's no difference between not detonating and really really really not detonating. Octane number does not refer to how fast it burns or how much energy is in there.

There are two octane number tests, motor (MON) and research (RON). Both are engine tests. They run the gasoline in a special test-engine at full load, and vary the compression ratio until it pings. How far they get determines the result (0-100). The difference between RON and MON is how they run the engine (timing, RPM, coolant temp, air temp, etc.).

In the US, we do both tests and use the average, (R+M)/2...sometimes called antiknock index (AKI). In most of the rest of the world, they only use RON. For most gasoline blends, RON is higher by about 10, so a RON of 95 in Europe is the same as 90 in the US, for the same fuel.

The Prius has an expansion ratio of 13. The compression ratio is less. Anyone who says the compression ratio is 13 is wrong. The computer doesn't ever let in that much air.

Gasoline is blended from different gasoline-like mixtures, usually called naphthas. Each blendstock has different properties that are blended to meet certain specs in the final product. Some of these properties are RVP, octane, olefin content, sulfur content, aromatics content, boiling range, and potential gum content. The final gasoline has specs on all of these, and the specs vary by where the gasoline will be sold. Energy content is not a spec'd property.

Premium gas is just blended to a higher octane number by adjusting the ratio of the blendstocks...more of this, less of that, etc. Sometimes the premium will end up with slightly higher energy content, sometimes less, depending on what the refinery needs to get rid of that day. There is no trend that premium has more energy.

If MPG is your only goal, then here's what you can do:

1. Find a station selling non-ethanol-blended fuel. This could add up to 4-ish % to your mileage. This is available in some areas, but where it is, it's usually more expensive. There are a few in my area, but they're about 5% more expensive...go figure.

2. Top Tier gas. The top tier certification is genuine. It's not trivial to meet, but only guarantees detergency for deposit control, not MPG. But, a deposit-free engine will run more efficiently.

3. Don't fill up when the station has a tanker there offloading. This urban legend is true, but pump filters take care of most of the problem. No effect on MPG, but could save a filter change.

4. Find a station that looks "well run"...you know, clean, all the lights working, etc. Chances are he's maintaining the equipment and buying the advertised gas.

 

Well, here in Oregon we are obligated to use 10% Ethanol all year long, State Law.

alfon

 

I use all regular grade with companies that make the top tier gas rating around me. You can go to the website at toptier.com. The ones I use is Chevron, Shell. Texaco and Conoco are in this group as well around me. Surprisingly BP is not on the list.

 

Here in Arkansas they have some crazy deals going on. I have heard stories from a friend who retired as a state gas inspector. His uncle was a state rep and got him the job, when he lost an election for some crazy scandal no one ever got around to replacing my friend.

He told me some horror stories about the pumps only fueling at 1/2 the rate they show, contaminants and water in the fuel, and even explained to me some of how the supply chain works.

Your post was highly informative and some I had heard from my friend. It is great to hear things like this from people who work in the business.

Oh, also my friend did tell me some great stories about how he only worked about 10 hours a week randomly inspecting stations, and how he would catch people using "farm grade" fuel in non farm vehicles. One was the guy who replaced his uncle in the state rep, which could be why he kept his job for so long.

 

+1

 

What really surprised me was the number of small market brands on the top tier list (post #18). High quality, but I bet at a lower price.

 

Mostly I agree with your posting. Just a couple of minor suggestions:

I believe it is the intake valves and though somewhat variable in angle, they are letting part of the charge back into the intake manifold.

This is correct about the blendstock but curiously, I found distinct differences in hill climb testing:

A Graham miniscanner can read MG1 torque that is fixed at 28% of the ICE torque. With ICE rpm, calculated torque and mass flow or fuel injection timing, we can calculate the specific fuel consumption. Before we had ethanol in our local gas stations, I was able to find:
These were repeatable results showing three brands, Shell, Chevron and Exxon had higher shaft output that was not found in the other tested brands, Texaco, BP, Conoco and Citgo. Measuring the energy content of gasoline remains an interesting problem and needs to be automated.

I am convienced that if we can get a good measure of MG1 torque, ICE rpm and fuel consumption, we can provide a specific fuel consumption display. It needs to be a scatter graph whose X axis is ICE rpm and Y axis is specific fuel consumption. This would make a major improvement in our fuel buying practices. The problem is automating it for the mass market.

Bob Wilson

 

Here in WI we can still get ehtanol free gas, ironically it's sold mainly at farmer used stores, co-ops, places like Fleet Farm. I have found that my milage goes up from 50mpg to 53mpg when I use non-ethanol gas. I haven't noticed any difference in brands.

 

I use good ol ARCO 87! works great! My car aint picky!

 

And why is that?

 

Well, I retired from Chevron USA, where I worked as an electronics technician for 17 years. The refinery where I worked is in Richmond, California. I was one member of a group that repaired, calibrated, and maintained the on-line analyzers as well as the state-mandated CEM (Continuous Emissions Monitoring) stack analyzers. I can assure you that Chevron refines it's gasoline from crude oil stock obtained from several sources, as does Shell Oil Company in Martinez California.