Chennai-based entrepreneur and blogger Kiruba Shankar's video of how attendants at a Chennai petrol station cheated him has evoked a strong response since it was released on Friday, with more than 2,000 likes and shares on Facebook.

"I just caught the staff red-handed at Bharat Petroleum fuel station on Anna Salai," Shankar wrote on his Facebook page. "They tried to steal Rs 700 worth of petrol."

Shankar said that the attendants tried to distract him when they were filling up his tank, and then reset the meter before it hit the value he had asked for when they thought he wasn't looking. This is one of the many tricks that petrol pumps sometimes pull on you.

Here are a few more.

1) A faulty meter

Some petrol pumps have rigged meters that start ticking even before petrol starts to flow from the hose. A motorist encountered such a meter at a station near Hosur in Tamil Nadu and created a scene at the pump. The manager gave him Rs 500 off.

2) A fuel hose longer than is required

Pumps save on a lot of petrol when they use long pipes. A perfectly good meter will show that a certain amount of petrol has been pumped out, but that amount hasn't reached your tank -- some of it is still in the pipe, and it goes back into the pump. Through the day, the number of litres that stations save can be enormous.

3) Sticking fingers firmly in the nozzle of the hose

This reduces the flow speed of the fuel and can save up to a litre at a time for the station.

4) Adulteration with naphtha

Naphtha is a byproduct of the petroleum distillation process. It is as dense as petrol and leaves no residue. Attendants mix some of it in the petrol, and you are none the wiser as you fill 'er up with less petrol than you bought.

5) 'Double-checking' the required amount

The attendant asks you how much petrol you want. You say you want petrol worth Rs 1,000. He stops at Rs 200 while configuring the meter, and reconfirms, and 'updates' the value by Rs 800. You might think that you are receiving petrol for Rs 1,000 -- but you are only getting petrol for Rs 800, as he has not actually reset the meter.