Some gasoline purchasing tips

[TDK]

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 memeber who also has a lot of similar experiance.

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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.

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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 (some of which can be taxable). I realize I'm fortunate in this regard, but I have also planned it and not abused it - over many years. If you have the oppertunity to make choices regarding salary or "other compensation" for employment, - in particular relating to transportation - choose wisely.

Good Luck

[TDK]

Bruce,

Sorry, double post due to some sort of site lag (has not happened before)?

Please delete whichever has fewer replies/activity.

Thanks

[mrcrx28]

So filling at night is acceptable as well right?(Since at night time its usually chilly-er) You said when the ground is at cold temp. Basic important rules are.

1. Fill during cold temps, either earlier morning or late night.

2. Fill with low speed

3. Fill at mid-mark on tank.

[TDK]

mrcrx28,

Well, I think it would be optimum to fill up near daybreak as opposed to late evening. The ground is probably warmest at sunset and gets progressivily cooler until daybreak - when the cycle repeats.

It would be interesting to see some temperatre-profile data from an undisturbed gasoline storage tank.

Thanks

[adallak]

Yeah, you probably can save $0.02 out of $50.00. I do not think underground temperature some 10 feet below the surface changes more than one degree during the day-night cycle. If you condense the vapor which escaped back to the tank you probably will get a few drops.

[JohnnyG]

Yeah, you probably can save $0.02 out of $50.00. I do not think underground temperature some 10 feet below the surface changes more than one degree during the day-night cycle. If you condense the vapor which escaped back to the tank you probably will get a few drops.

adallak is right on this one. This e-mail has been around, and this is the item that I have the single biggest problem with. Below ground temps stay around 55° in most of the northern US, so forget this tip.

Also, there are no turbine meters or flow meters involved in measuring this low flow/low volume commodity. Not at this level. They employ PD meters, positive displacement. Now, at my loading rack, we used to employ turbines, but they are now a thing of the past for us. I can currently load 3000 gallons of fuel into a truck at an accuracy of +/-.10 gallon using the new Smith Prime 4 PD meters! This does not mean that gasoline dispensers can maintain that same accuracy and in fact will vary more than this in 5 gallons dispensed. Most states use outdated simple equipment for testing gasoline dispensers......a "calibrated" 5 gallon can. Their passing tolerances are generally higher than .1 gallon/5 gallons. this used to be fine, but I think we'll be hearing more about this in the near future.

I have a few small issues with a few other statements in the e-mail, but generally the rest of that advice is logical.

I'm on my 35th year in the oil business.

[daniel812]

i manage a gas station and our underground temps stay at 57 degrees. I personally dont think that these tips will make any difference. Liquid can only fill up to a cetain height in your fuel tank no matter what time of day. Your car has strict emission controls for fuel vapors.

[95SevilleSLS]

Yeah, you probably can save $0.02 out of $50.00. I do not think underground temperature some 10 feet below the surface changes more than one degree during the day-night cycle. If you condense the vapor which escaped back to the tank you probably will get a few drops.

adallak is right on this one. This e-mail has been around, and this is the item that I have the single biggest problem with. Below ground temps stay around 55° in most of the northern US, so forget this tip.

Also, there are no turbine meters or flow meters involved in measuring this low flow/low volume commodity. Not at this level. They employ PD meters, positive displacement. Now, at my loading rack, we used to employ turbines, but they are now a thing of the past for us. I can currently load 3000 gallons of fuel into a truck at an accuracy of +/-.10 gallon using the new Smith Prime 4 PD meters! This does not mean that gasoline dispensers can maintain that same accuracy and in fact will vary more than this in 5 gallons dispensed. Most states use outdated simple equipment for testing gasoline dispensers......a "calibrated" 5 gallon can. Their passing tolerances are generally higher than .1 gallon/5 gallons. this used to be fine, but I think we'll be hearing more about this in the near future.

I have a few small issues with a few other statements in the e-mail, but generally the rest of that advice is logical.

I'm on my 35th year in the oil business.

I agree, another thing was the last part where they mentioned the truck filling up the tank. There are filters at the pumps so you would not get a piece of dirt up from the tank. If you're filling up at a place with no filters and are getting dirt, I wouldn't be going there anymore.

[adallak]

I replaced my gas tank at 152.000 miles. It was ABSOLUTELY clean inside.

[95SevilleSLS]

I replaced my gas tank at 152.000 miles. It was ABSOLUTELY clean inside.

Same here, my 90 Deville was clean as a whistle when I replaced the pump at 188,000 miles.

[daniel812]

also - all gas stations have filters in their tanks to filter out anything in the fuel, and obviously all cars have filters also.

[95SevilleSLS]

also - all gas stations have filters in their tanks to filter out anything in the fuel, and obviously all cars have filters also.

Technically fuel injected vehicles have two. The sock on the fuel pump and then the inline filter. But like you said, there are filters at the stations. You can tell sometimes if their filter needs to be replaced. It pumps really slow.