Kerosene oil is regarded as more suitable than petrol in oil lamps because it is less volatile. This means that it has a higher flash point, which is the temperature at which it can ignite. There are several reasons why this makes kerosene a better choice for oil lamps:

1. Safety: The lower volatility of kerosene makes it safer to use in oil lamps. Since it has a higher flash point, it is less likely to ignite accidentally. This reduces the risk of fires and explosions, making it a safer option for lighting purposes.

2. Stability: Kerosene is more stable than petrol. It has a longer shelf life and does not degrade as quickly as petrol. This means that kerosene can be stored for longer periods without losing its quality or becoming unusable. Petrol, on the other hand, can deteriorate over time, which can affect its performance and safety.

3. Odor: Kerosene has a milder and less pungent odor compared to petrol. This makes it more pleasant to use in oil lamps, especially in indoor settings where the smell can be more noticeable. The lower odor of kerosene also reduces the chances of headaches or respiratory discomfort that can be caused by strong smells.

4. Efficiency: Kerosene is more efficient than petrol in oil lamps. It burns more slowly and consistently, providing a steady and reliable source of light. This means that a lamp filled with kerosene will last longer and require less frequent refilling compared to a lamp filled with petrol.

5. Availability: Kerosene is more readily available and accessible in many parts of the world compared to petrol. It is a commonly used fuel for various purposes, including lighting. This makes it easier for people to obtain kerosene for their oil lamps, ensuring a reliable source of lighting.

In conclusion, kerosene oil is regarded as more suitable than petrol in oil lamps due to its lower volatility, which enhances safety, stability, odor, efficiency, and availability.