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According to the Shell engineers ethanol gasoline has a 90-day shelf life. VP Racing has a gasoline with a 2-year half life. I know that the Revs Institute uses the VP gasoline exclusively. Here's my article on all of this. Richard Newton
Yes 3 months later bin it or if you have 1/4 of a tank mix it with a full tank, or put some 100 octane to raise the octane level and so on...actually I would not drive it before doing so.
All that because the car tanks are obviously vented ....
In a sealed Jerry can ( with correct air gap) you can keep them for a long time,
Ethanol is alcohol and gasoline is petroleum. They don't mix well, and they don't stay mixed. Gasoline is made as rbob...reformulated blendstock for oxygenate blending. Rbob has an octane of 83-84. So when you add 10% ethanol you get 87 at the pump.
So since ethanol and gasoline can't really stay mixed and as ethanol takes on water from the armosphere, it accelerates the separation, the way it's mixed is as close to the pump as possible. A 10k gallon truck is driven to the tank farm, and filed w 9k of rbob, and then it goes to the ethanol tank for a splash blend of 1k ethanol, and then off it goes to the pump.
There are also gas stations that have separate tanks and blending pumps. They can regulate the qty of ethanol in their gas and blend more up to the amount stated on the pump itself.
Racing gas uses other high octane blend stocks to raise the octane level. These octanes like alkylate, have a much higher btu than ethanol and so bigger bang and more potential for power. Ethanol is 117 octane but low btu means the more ethanol, the smaller the bang and the lower the potential for power, but since it's high octane, you can compress more fuel to compensate.
Anyway. The separation of the two in the tank is the reason for the short shelf life...
Oh. And. Ethanol is not green. Never was green, and should be banned due to the damage we are doing to the earth by trying to grow fuel. Just my 2 cents....having worked many years very closely with the production and sale of ethanol. Good idea. Terrible execution on the part of our government.
Oh. And. Ethanol is not green. Never was green, and should be banned due to the damage we are doing to the earth by trying to grow fuel. Just my 2 cents....having worked many years very closely with the production and sale of ethanol. Good idea. Terrible execution on the part of our government.
Well said. I've seen the consequences of that stuff in automobile fuel systems for years and none of it is any good. Most of them get very expensive over time.
Sorry, now I am really confused. Does that mean the full tank of Shell 91 gas I have in my car before I put it away is no longer good fuel and should be removed from my car???
Consensus on this forum was that the Shell gasoline was the favorite for our cars.....
All finished gasoline at the pump in the United States is the same. All the stations get their gas at the same
Tank farms in the same way. It's generic. There is no such thing as "cheep gas". They litterally are all 100% identical. Shell puts a useless splash of some inexpensive material into their gasoline, some blendstock that makes no difference at all to your car, and calls it "nitro something" and they charge more. But what they are doing is raising their margin and the pump price at the same time. It's a joke. Take a drive to Perth amboy New Jersey someday and take a look.
Oh. And as to old gasoline. Put your car away un-full, and splash a few gallons of new gas in it when you go to start it up. You can also use sta-bil. It'll help w the separation.
Regardless, start it and drive it. You aren't hurting anything. You hurt it more by letting it sit.
I worked for the old Atlantic company in PA. Most of our gas came from the Mobil refinery.
We have a bunch of Sunoco stations in FL. The nearest Sunoco refinery is in PA. Sunoco buys all their gas on the open market here in FL.
The name on the sign means nothing.
Here's an quote from an engineer at a major oil company.
Gasoline is a commodity that is freely mixed in pipelines and storage depots. It's bought and sold by chemical spec (octane, emissions, etc) and sales region, not by origin. Even BP stations or Shell stations don't necessarily sell gas from a BP refinery or Shell refinery. The branded additives are added at the local distribution center or at the gas station itself.
What's funny is that my other car (bmw) has an N54 3.0L twin turbo engine, and the guys on those forums want all the ethanol they can get.
Only because they don't know what they are likely tuning the motor to run the higher octane.
Ethanol is 117 octane. It has a lower btu than gasoline, but...since its higher octane and therefore less volatile, you can massively increase your compression ratio and tune the motor to run hotter and get more power out of it.
But. Short of changing the motor, the reality is this...more ethanol equals less power. It's just the way it goes. Speaking purely of 91 octane conventional gasoline (which isn't sold at 99% of gas stations in the US today), and what is sold, which is 91 octane w up to 12% ethanol. Conventional gasoline (gasoline w/out ethanol) has a higher btu and explodes w more power. So without tuning and major engine changes, you get less power with ethanol in the gas. This is why your gas mileage goes down when using ethanol blended gasoline over using conventional.
03-05-2016, 09:43 AM
Gasoline
