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Some gasoline purchasing tips


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Dear All,

A number of you may have already seen this email, (between ****) that is going around from a person in the gasoline trade. I believe we have a member who also has a lot of similar knowledge.


I don't know what you guys are paying for gasoline.... but here in California we are also paying higher, up to $3.50 per gallon. But my line of work is in petroleum for about 31 years now, so here are some tricks to get more of your money's worth for every gallon..

Here at the pipeline where I work in San Jose , CA we deliver about 4 million gallons in a 24-hour period thru the pipeline. One day is diesel the next day is jet fuel, and gasoline, regular and premium grades. We have 34-storage tanks here with a total capacity of 16,800,000 gallons.

Only buy or fill up your car or truck in the early morning when the ground temperature is still cold. Remember that all service stations have their storage tanks buried below ground. The colder the ground the more dense the gasoline, when it gets warmer gasoline expands, so buying in the afternoon or in the evening....your gallon is not exactly a gallon. In the petroleum business, the specific gravity and the temperature of the gasoline, diesel and jet fuel, ethanol and other petroleum products plays an important role.

A 1-degree rise in temperature is a big deal for this business. But the service stations do not have temperature compensation at the pumps.

When you're filling up do not squeeze the trigger of the nozzle to a fast mode. If you look you will see that the trigger has three (3) stages: low, middle, and high. In slow mode you should be pumping on low speed, thereby minimizing the vapors that are created while you are pumping. All hoses at the pump have a vapor return. If you are pumping on the fast rate, some other liquid that goes to your tank becomes vapor. Those vapors are being sucked up and back into the underground storage tank so you're getting less worth for your money.

One of the most important tips is to fill up when your gas tank is HALF FULL or HALF EMPTY. The reason for this is, the more gas you have in your tank the less air occupying its empty space. Gasoline evaporates faster than you can imagine. Gasoline storage tanks have an internal floating roof. This roof serves as zero clearance between the gas and the atmosphere, so it minimizes the evaporation. Unlike service stations, here where I work, every truck that we load is temperature compensated so that every gallon is actually the exact amount.

Another reminder, if there is a gasoline truck pumping into the storage tanks when you stop to buy gas, DO NOT fill up--most likely the gasoline is being stirred up as the gas is being delivered, and you might pick up some of the dirt that normally settles on the bottom. Hope this will help you get the most value for your money.


From TDK: I can see good science and logic in most of the above tips. But, I will have to think about the pump nozzle position tip.

Depending on the meter technology, there may be a point where the pump's meter is "optimized" for you or the gasoline company. For example, some types of flow meters do not register at very low flows. Wikopedia notes that turbine-type meters are used with electrical pickups. Those sort of meters are not a positive-displacement device, so some turn-down problems may be possible.

Bear in mind that I'm not suggesting that you test dozens of pumps at various flows into Mason jars....

However, I also have the following advantages regarding fuel:

1. We trip-drive drive a 99' Deville that gets an honest 23-24 mpg at 82mpg.

2. She town-drives her new Rabbit only a bit, and it is easy on gasoline.

3. We town-drive my relatively-new company pickup the most. Not to brag, but in this case - the majority of fuel and all the other costs are on my expense account and part of my compensation.

Good Luck

Add power to leave problems behind. Most braking is just - poor planning.
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