On social media, there are a few theories relating to refuelling a car. One of the more popular ones is that when fuel is pumped at a fast rate – when the handle on a fuel nozzle is depressed completely – you’ll actually get less fuel than what you paid for.

This theory arose due to the claim that petrol more easily vaporises and is “lost” into the air when pumped at a fast rate. As such, it’s been suggested that pumping petrol at a slower rate minimises this loss, but is this fact or fiction? Are people wasting more of their time and of others by refuelling slowly at the pumps?

To put the theory to the test, Shell Malaysia Trading managing director Shairan Huzani Husain, who is also known affectionately as “Pak Cik Shell,” uploaded a video to his personal Instagram account featuring a self-made experiment.

In the video, Shairan used a volume gauge to measure the amount of petrol coming out of a fuel pump, which was set to deliver 10 litres of RON 95 petrol. The experiment involved first pumping the fuel at a slow rate, followed by another round at a much faster rate. On both occasions, the end result was the same, with the gauge showing 10 litres delivered.

However, it should be noted that fuel evaporation when refuelling can be affected by temperature and weather factors, although the difference in volume is miniscule. Based on the experiment, it looks like there’s no real benefit to refuelling slowly, especially when others are waiting for their turn.