You've probably seen videos of people shaking or rocking their cars while filling it up with petrol, supposedly in an attempt to get more fuel in.

Here's an instance of it:

Recently, episode 32 of CNA's show Talking Point discussed this misconception on filling up one's tank.

A short snippet of it has been widely shared on Facebook group ROADS.sg:

Rocking does not get more fuel into tank

In the video, car workshop director Vincent Emmanuel Lee explained that it is that the time that has passed, and not the rocking, which allows more petrol to be introduced to the tank.

This was the exchange between Lee and the presenter:

Lee: When we pump the petrol into the tank, it creates foam and vapour (which) occupies the tank. When we wait for the vapour and foam to dissipate, that's when you can pump more petrol into the tank.

Presenter: By shaking it, doesn't that help the vapour dissipate faster?

Lee: No, it doesn't.

To illustrate his point, he likened the act of pumping petrol to pouring a fizzy drink in a glass.

"As we wait, the foam will actually go down," he explained. "It actually creates more space for you to introduce more petrol in."

But, is shaking the car bad for it?

Lee also clarified that shaking the car is not bad for it per se.

However, overfilling the tank is detrimental as it may cause the petrol to enter the Evac system, the fuel evaporation system which helps remove vapour from a fuel tank.

"(Overfilling the tank) actually causes the petrol to be able to go into the Evac system. And the cost of replacing the Evac system could be very high."

You can watch the full Talking Point episode here.

Top photo from iStock photo and video screengrab.

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