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Oct 22, 2023

Don't buy these 4 gas station refueling myths

Those "hacks" won't actually save you money at the pumps, but you might find these tips helpful

Do you top up your car's gas tank in the morning rather than the afternoon? With the nozzle trigger pushed all the way down rather than just half-way?

If you think you’ve worked out hacks to get more out of your car's fuel bill on the pump end, we’ve another for you: don't waste your time.

There are tonnes of myths about variables you control while filling up at the gas station, we thought we’d debunk a few.

That Facebook post swears by it: Refueling on a chilly morning will give you more for your money than pumping in the middle of the day, when the temperature has risen.

It seems logical. We all know when temps drop, liquid volume shrinks and density goes up, like in that bottle of sparkling water you forgot in the freezer. So it's natural, you think, that filling your tank when it's cold will get you more (temporarily denser) gasoline.

While the science checks out, generally, a gas station's supply tanks are buried so deep underground their temperature barely fluctuates. No matter what Mother Nature does up here, the density of the fuel down below will tend to be more or less the same.

Furthermore, in places where the temperature might fluctuate enough to make a difference, most gas stations will compensate by "correcting" the volume so you’re not paying less or more depending on density. "An electronic device called an automatic temperature compensator (ATC) measures the temperature of the fuel during delivery and automatically calculates the amount of fuel as though it had been delivered at 15 °C," explains Measurement Canada.

Use of these ATCs is optional on gasoline and diesel pumps in Canada, but you’ll know if the station employs them because you’ll see a "Volume Corrected to 15 °C" sticker on the pump. A "vast majority" of stations in Canada do, and have been for over 20 years.

What will make a difference is making a detour specifically to refuel in the morning. That wastes fuel you wouldn't burn if you just stopped at a station en route later in the day.

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Rather than when you fill up, maybe you’re more concerned with how you fill up. You press the handle on the nozzle hard, convinced going half-measure lets air enter the system, leaving less space for hydrocarbons.

Well, conspiracy theorists, no matter how hard you do – or don't – squeeze that trigger, the volume of gas entering your car's tank stays the same.

An electronic meter in the pump measures the volume of gas flowing into your tank. It operates at all flow rates, as required by Measurement Canada, whether you’re trickling it in slow as possible or rip-roaring at 30-litres-a-minute.

You know that little sticker showing the pump's last inspection date? That's there because a government agency monitors the accuracy of all our measuring devices, from gas pumps to food scales.

It's a good deal for everyone. Gas stations don't want you to get more gas than you paid for, and consumers don't want less.

But if ever you fill a jerry can to the brim only to discover the reading on the pump doesn't match the canister's capacity, Measurement Canada reminds you that declared capacity is only approximate — as is your car's tank.

If you’ve ever wondered what keeps the fuel pump in your car working, we’ve got the answer: gasoline. Yes, fuel itself cools and lubricates the pump that draws that fuel from tank to engine.

In other words, don't wait for the "empty tank" light to go on before visiting the gas station. "Playing chicken with your gas gauge is a fool's errand," writes my colleague Lorraine Sommerfeld. That dashboard warning is not just teasing you.

So how close to empty can you get? Experts recommend to never let the gas gauge get below a quarter of a tank. Those experts may have discounted Canada's harsh winters and the fact condensation can collect in empty tanks, then freeze in our gas lines when Mother Nature plays chicken with outdoor temperatures.

We recommend keeping your gas tank three-quarters full. Our mechanic-in-residence, Brian Turner, notes a full tank also adds weight, and therefore traction, in winter. Like sandbags, but safer.

On the other hand, filling your gas tank to the brim isn't great either. When the pump handle clicks shut the first time, you’re done refueling.

Stop there. Don't try to rock the car and keep pumping, or add more fuel because the price is good right now, or you’ll risk damaging the fuel tank evaporative emissions control system. Said valving is designed to capture excess fumes from your tank before they vanish into the atmosphere. But it is not designed to capture the fuel itself.

Flooding it with gas only keeps it from doing its job, possibly causing an expensive failure of the venting-slash-evap systems and maybe illuminating a check-engine light.

We leave you with a tip which might not save you much fuel but could prevent some road – er, gas station? – rage. It is, simply, know which side your car's gas door's on before heading to the pumps.

How can you tell without lowering your window and popping your head out? Look at your dashboard's fuel guage. See the little arrow (usually next to the fuel pump symbol)? It points to the side with the opening.

Seems obvious — but ask your friends how many of them knew about it. You might be surprised.

A journalist for three decades, and exclusively in the automotive sphere since the year 2000, Nadine Filion likes to focus on car advice for everyday consumers. Her research and writing have won her the Canadian Automotive Journalist of the Year award three times.

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