Evaluating petrol from crude oil prevents issues like engine knocking, which is also known as pinking, ensures proper volatility for starting, controls harmful sulphur content, and maintains desired octane ratings, all crucial for engine performance, efficiency, and environmental compliance, ensuring it meets specific standards before sale. Pinking (Pre-ignition) is the process whereby straight-chain alkanes (like heptane) in raw petrol ignite too early under compression, causing engine knocking (pinking).

Reforming: This process improves quality by rearranging molecules into branched alkanes and aromatics (like iso-octane), raising the octane rating and preventing pinking.

Cracking: Breaks large, heavy hydrocarbons (from heavier fractions) into smaller, more valuable gasoline-range molecules, increasing the quantity of petrol, but the resulting mix might still need reforming.

Pyrolysis: An extreme thermal cracking (high heat) that produces basic petrochemical building blocks (like ethylene, propylene) for plastics, not finished petrol, and is energy-intensive.