1. Open the bonnet of the car.
2. Locate the oil filler cap. On the 1999 VW Polo, this is usually a black plastic cap marked with the oil symbol located on the top of the engine, towards the back.
3. Unscrew the oil filler cap.
4. Use a funnel to add engine oil to the engine. The oil level should be between the "min" and "max" marks on the oil dipstick.
5. Replace the oil filler cap and tighten it securely.
6. Check the oil level after a few days of driving to make sure it is still within the correct range.
