More gas for your $$$$$ - say it IS so...please?

Spam. Who'd have thought 100 years ago when they invented the savoury potted meat, that the word would eventually become one of the more feared in the English lexicon. And not feared in a "arrgh arrgh, its got my leg" kind of way, but more of a "oh for fucks sake, its not what I think it is" eye rolling type of response. Is my wanger really that small? Do my boobs really need to be bigger than they already are? Is investing in in that pharmaceutical company really going to fulfil me as a person? Or is all this spam just needlessly thrashing the worlds networking devices?

And some spam isn't even trying to elicit money - its one of those ones that unless you look closely at what its saying, and think objectively, it may sneak past the radar and encourage you to forward it on to someone else. The dreaded S-SPAM (Sneaky-Superficial Pesky and Annoying Message) that you end up getting from a well meaning work mate, your sister-in-law or the guy you know at the coffee shop who just got online for the first time and has your email addy for some reason. A majority of these run the same gambit - pull heart strings, then bullshit or threaten the reader.

My snake/dog/penis was trapped/shot/fired from a cannon and only through extensive surgery/gods will/serious whacking will it ever be able to work/walk/rummage through my sock drawer.
Please send this on to 5 million people and you'll see a fire start spontaneously in your hard drive/a cool video of dancing voles/me coming through the front door with an axe.

It was exactly this kind of mail that I received a yesterday. A well meaning, but misguided work....dude (I cant say mate, I don't know the guy!) sent it to everyone in the building. 500 people had that eye rolling moment when you see someone on the internal mail list you've never heard of sending an email with multiple $$$ signs in the subject.

So, "get to the point" you say, and quite rightly as well. The subject was "More gas for your $$$$$" and as I went to delete it, I paused and thought "thats a new one". More gas? I've seen more inches, boobs, drugs, pr0n, shares, watches, Nigerian dollars and degrees, but gas? Was someone hoping to up my flatulence rate? Ok ok - I couldn't help it - everyone loves the fart jokes. Lets examine the contents. Of the email. Not the fart.

In this day and age, with petrol prices sky rocketing, we are more concious than ever about when we use the car and for how long. So this email played on that fear and I was sucked in. Here's a basic run down :

It was someone in Durban (SA) who worked in the petroleum industry. They spoke about the types of fuel the handled every day.

1) The first tip was to only fill up your car early in the morning because "all service stations have their storage tanks buried below ground. The colder the ground the more dense the fuel, when it gets warmer petrol expands, so buying in the afternoon or in the evening" you get less bang for your buck.
2) Tip #2 was don't fill too fast because "the trigger has three stages: low, middle, and high. In slow mode you should be pumping on low speed, thereby minimizing the vapours that are created while you are pumping. All hoses at the pump have a vapour return. If you are pumping on the fast rate, some of the liquid that goes to your tank becomes vapour. Those vapours are being sucked up and back into the underground storage tank so you're getting less worth for your money.
3) Tip #3 was only fill when your tank is half full. This, it was reasoned was due to "the more fuel you have in your tank the less air occupying its empty space" and "petrol evaporates faster than you can imagine".
4) And finally, tip #4 is don't fill straight after a truck has delivered the fuel to the station, as "the petrol/diesel is being stirred up as the fuel is being delivered, and you might pick up some of the dirt that normally settles on the bottom."

The message was ended with a lovely "Hope this will help you get the most value for your money".

Now it may be that someone has decided to send helpful information around the world via forwarded email, but being the cynical bastard I am I seriously doubted it. I decided to spend 30 mins checking the veracity of this email because a) if it was right, I could save some pingers at the pump, and b) if it was wrong I could use it as blog fodder. Lets look at the claims :

1) Cold fuel is better than warm fuel.
It said in the email that a 1°C rise would make a big difference in what you pay at the pump. Nearly all petrol stations store their petrol underground. The ground temperature change over the course of a day is not big for something that deep - probably 1 or 2 °C during the course of a day (data from New Zealand meteorological stations in Wellington). But lets use the 1°C in the email. Assuming that a motorist typically bought 40 litres of petrol per week at $2.00 per litre, and assuming that by carefully choosing to fill up at a particular time of day said consumer could realize a 1% savings, the total savings to be gleaned over the course of a year is about $40. Would that reward really be worth the potential inconvenience of adhering to a rigid fill-up schedule week after week?
I checked a report done by the National Weights and Measures in 1999 and they state the following figures :

Hot fuel Temperature > 24°C Approx. 1% volume difference from 15°C
Warm fuel Temperature > 17°C Approx. 0.25% volume difference from 15°C
Cool fuel Temperature < 13°C Approx. 0.25% volume difference from 15°C
Cold fuel Temperature < 6°C Approx. 1% volume difference from 15°C

This means there would have to be a 9°C change to realise that 1% savings. That's way outside the 1 or 2 °C on an average New Zealand Day.

2)Pour your petrol slowly
Advocates maintain that pumping gas more slowly produces fewer vapours, and therefore consumers get more for their money by using slower settings on pumps (because less gasoline is lost to vaporization). Critics assert that the amount of vapour loss produced during the pumping process is so small as to be economically insignificant to the ordinary consumer. And one has to consider the time factor: Is the aggregate amount of time you're going to lose by using only the slowest delivery setting at every fill-up really worth whatever modest amount of money you might save?

3)Fill your tank when its half full
Some advanced gasoline filtration systems claim to recover about 2% of the fuel lost by evaporation from gas station storage tanks. Is that savings really worth essentially halving the storage capacity of your car's gas tank (thereby requiring you to stop for gasoline twice as often as before)? Assuming that our typical consumer bought gas once a week, and that the fill-up process averaged a modest 8 minutes (including the time to get to a gas station, to wait in line if the pumps are all busy, to pump the gas, to pay for the purchase, and to get back on the road), said consumer would be spending an extra 7 hours per year pumping gas to achieve these savings. Is that a good trade-off of time vs. money?
The report by NWM also states :

"With modern petrol engine burning about 98% of the fuel entering the cylinders and with catalytic converters burning about 75% of unburnt fuel leaving the engine, total emissions from the engine exhaust represent only about 0.5% of fuel usage. Vapour losses from ullage spaces are likely to be of the order of 0.15-0.2% at each of the stages listed above and the fuel supply chain emissions are therefore comparable with vehicle operating emissions"

0.15% - 0.2%, which if we use the example from point 1 (40l x $2 x 52 weeks = $4160/year) we would see a return of $6 to $8 per annum. Not very much return on the wasted time.

4)Sediment in the tank
Most sources agree that deliveries from tanker trucks do stir up particles of dirt and sludge in gasoline storage tanks, but that this isn't really much of an issue for the ordinary motorist. Service stations are required to have filters that trap dirt and sludge, and modern cars also have fuel filters, so a bit of stirred-up dirt doesn't really pose much of a potential to adversely affect your car. And again, one has to consider the trade-off. On the (probably infrequent) occasions when you arrive at a gas station at the very same time a tanker is filling the station's tanks, is it really worth the time and expense to leave without filling up and drive off to a different service station just to avoid something that likely isn't much of a concern in the first place?

If you've skipped all of this and are looking for the punch line, here it is - don't believe everything you receive in the inbox, but don't be overly sceptical either. Check your facts, look for evidence supporting and contradicting both sides (check the veracity of the sources too) and make up you own mind.

For the best info on making your car go further, I suggest you read the following sites which have the best info for motorists and its basic stuff backed up by simple science. It by far and away beats anything listed above in terms of fuel saved and it can be as simple as modifying your driving habits. Check it out.

New Zealand Government website FuelSaver

Consumer.org - Consumer Protection Non-profit Organisation

BTW - this email is listed on Snopes.com and they say this :

This collection of purported money-saving tips for buying gasoline is another item difficult to classify as strictly true or false. It's not completely false in that one or more of the tips might actually result in some savings (however modest), but it can't fairly be classified as true either, as the practical utility of all of these tips is disputed, and the economic gains to be had from following them is highly questionable.