Is it true that when you go to pump premium gas almost a gallon of the gas that was pumped by the last person (that is usually regular) is left in the pump and hose and winds up in your gas tank?

 

That's why I use Diesel . . .

 

complete BS. the pumps and controls etc etc are in the pump you pull up to and even on a single hose gas pump you get very minimal if any or enought to make any difference in mixing of fuels.

 

Squeeze the handle before you start. How much came out? Nothing? Why is there nothing in the hose after the pump is shut down? Now how much regular gas do you think you're getting?

Time for the myth busters to get involved.

 

Maybe that is why my scooter runs a little better every once in awhile, I'm getting a gallon of premium someone left in the hose when I fill up with my cheap azz 87

 

The Blend Valve

Safety Measures
As the customer pumps the gas mixture of his or her choice into the car's gas tank, any number of accidents could happen -- most of them attributable to human error.

If an absent-minded customer drives away with the nozzle still inserted in the tank, the hose is designed to break into two pieces. One remains with the car and the other with the dispenser. Check valves on both sides of the breaking point prevent fuel from leaking out of either half.


One of the first things that a customer will notice at the pump is the variety of choices offered. In most cases, a dispenser will offer several grades of gas -- sometimes as many as five -- each with a different octane rating. The desired octane rating is usually chosen simply by pushing a button. Does this mean that there are five different underground tanks feeding into that dispenser, each offering a different grade of gas? That's not usually the case. In fact, the dispenser can produce as many grades as it wants from as few as two underground tanks, as long as one tank contains the highest grade of octane available at that station and the other contains the lowest. The grades are blended together at the pump -- not unlike the way you'd blend gin and vermouth to make a martini -- producing a kind of octane cocktail. The precise proportion in which the grades are blended determines the octane of the gas that enters the customer's tank.

This feat of gas pump bartending is performed by something called a blend valve. This valve has inputs consisting of two grades of gasoline, each from different tanks. A single, moveable barrier called a shoe is connected to both in such a way that it can be moved across the inputs with a single motor-driven ratchet. As the ratchet opens one valve, it closes the other valve in precise but opposite proportion. This means that when one valve is, for example, 90 percent open, the other valve is 10 percent open, creating a mixture that consists of 90 percent of one octane and 10 percent of the other. By shifting the ratchet back and forth, the blend valve can produce any octane of gas, ranging from the highest to the lowest grades stored in the tanks -- and all octanes in between

 

5 Here in Tennessee were lucky to have 3.

They do mix the reg and ethel for the mid.

 

After an education like that, I'd like to retract my weak attempt at a joke. That's some interesting info.

 

Thank U, Mr Wizard (I LOVED that show when I was a kid!!!!) THAT'S precisely how it wurx !!!!

 

I don't remember the last time I saw a "one nozzle" that pumps all blends around here. We don't have Sunoco here, the brands we do have are all seperately hosed.