Choosing the right engine oil for your car

Engine oil is more than just a lubricant—it’s a critical component that ensures your vehicle runs smoothly, efficiently, and reliably. It reduces friction between moving parts, helps regulate engine temperature, protects against wear, and prevents corrosion. Choosing the wrong oil can lead to decreased performance, higher fuel consumption, and, in severe cases, engine damage.

According to data from the International Lubricant Standardization and Approval Committee (ILSAC), using the recommended engine oil can improve fuel efficiency by up to 3–5% and extend engine life by several years. With hundreds of oil types, grades, and formulations available on the market, understanding how to select the correct engine oil is crucial for maintaining your car’s performance.

Understanding Oil Viscosity

One of the most important factors in choosing engine oil is viscosity, which refers to how thick or thin the oil is. Viscosity is indicated by numbers like 5W-30, 10W-40, or 0W-20.

• The first number (e.g., 5W) indicates the oil’s flow at low temperatures, ensuring your engine is protected during cold starts.
• The second number (e.g., 30) represents the oil’s thickness at operating temperature, providing adequate lubrication under heat and pressure.

For most modern vehicles, multi-grade oils like 5W-30 or 0W-20 are recommended, offering protection across a wide range of temperatures. Always refer to your vehicle’s owner manual to identify the correct viscosity rating. Using oil with incorrect viscosity can increase engine wear or reduce fuel efficiency.

Synthetic vs. Conventional Oil

Engine oils are generally divided into conventional, synthetic, and semi-synthetic types.

• Conventional oil is suitable for older vehicles with standard engines and provides basic lubrication at a lower cost.
• Synthetic oil offers superior performance in extreme temperatures, better oxidation resistance, and enhanced engine cleanliness. It is recommended for modern vehicles, high-performance cars, and long oil change intervals.
• Semi-synthetic oil combines the benefits of both, offering improved protection over conventional oil while being more affordable than full synthetic.

In 2024, synthetic oils accounted for more than 60% of passenger vehicle oil sales worldwide, reflecting their increasing importance for modern engines.

Considering Engine Type and Mileage

The type of engine and the car’s mileage also influence the oil choice.

• Gasoline engines typically require lighter oils like 0W-20 or 5W-30.
• Diesel engines often need heavier oils or oils specifically formulated to handle soot and high compression.
• For high-mileage vehicles, oils with additives that reduce leaks and oil consumption can prolong engine life.

Using the correct formulation ensures optimal lubrication, prevents sludge buildup, and maintains engine efficiency.

Additives and Special Formulations

Modern engine oils include various additives that improve performance:

• Detergents keep engine parts clean by preventing deposits.
• Anti-wear agents reduce friction on moving components.
• Viscosity index improvers ensure consistent performance across temperature ranges.
• Corrosion inhibitors protect metal surfaces from rust.

Some oils are specifically designed for turbocharged engines, high-performance vehicles, or hybrid systems. Always check the API (American Petroleum Institute) and ACEA (Association des Constructeurs Européens d’Automobiles) ratings to ensure compatibility with your engine.

Changing Oil Regularly: Key to Longevity

Even the best oil loses effectiveness over time. Most manufacturers recommend oil changes every 5,000–10,000 miles for synthetic oils and every 3,000–5,000 miles for conventional oils, depending on driving conditions. Severe driving situations—like frequent stop-and-go traffic, towing, or extreme temperatures—may require more frequent changes.

Regular oil changes prevent sludge accumulation, maintain fuel efficiency, and protect engine components, ensuring long-term reliability. Skipping oil changes is one of the most common causes of premature engine failure.