What is the best oil for a petrol engine?
The best oil for a petrol engine isn’t universal; it depends on your car’s specifications, your climate, and how you drive. In most cases, a high-quality synthetic oil that meets the manufacturer’s requirements is the safest default choice.
Key factors that determine the best oil
Choosing the right oil starts with understanding what your engine actually needs. The following steps help you align with the carmaker’s guidance while accounting for your conditions.
- Check the owner's manual for the recommended viscosity grade (for example, 0W-20, 5W-30) and the API/ILSAC specifications (such as API SP and ILSAC GF-6).
- Confirm the oil meets the engine’s approvals for your vehicle, including any OEM-specific requirements (for instance, VW 504.00/507.00 or GM dexos1 Gen 2).
- Consider climate and driving patterns. Cold climates often favor lower first numbers (0W or 5W), while hot climates may lean toward higher second numbers (30, 40) for protection at high temperatures.
- Decide between conventional, synthetic, or synthetic blend based on engine age, turbocharging, and driving style. Modern engines and turbocharged setups typically benefit from synthetic oils.
- Verify the recommended drain interval and whether your vehicle uses an oil life monitor (OLM). Do not extend intervals beyond what the manual allows.
- Choose a reputable brand and ensure the oil is stored in proper conditions and replaced with a new filter at the specified service interval.
Following these steps helps ensure compatibility, protection against wear, and adherence to emissions and efficiency standards.
Oil types and when to use them
Different oil types offer various trade-offs in protection, cost, and longevity. Here’s a quick guide to what they typically deliver for petrol engines.
- Conventional mineral oil: Cheapest option, suitable for older engines with simple designs and longer-known maintenance histories. Generally requires shorter drain intervals and may not provide the protection needed for modern turbo or high-stress engines.
- Synthetic oil: Offers superior protection across temperature extremes, better deposit control, and the longest drain intervals. Widely recommended for modern, high-performance, or turbocharged engines.
- Synthetic blend: A middle ground that combines some synthetic protection with lower cost than full synthetic. Good for drivers seeking better protection without the full synthetic price tag.
- High-mileage oil: Formulated with seal conditioners and additives aimed at older engines with higher mileage (often 75,000 miles / 120,000 km and up). Helps reduce oil leaks and improve damping of engine wear.
In practice, the best choice is the oil that matches your engine’s age, condition, and the climate in which you operate, while meeting the manufacturer’s approved specifications.
Specifications to look for on the bottle
Oil bottles carry multiple certifications and viscosity indicators. Knowing what to look for helps ensure the oil will perform as intended in your engine.
- API SP or higher: The current standard for gasoline engines, ensuring protection against wear and deposits.
- ILSAC GF-6A or GF-6B: Global performance standard for gasoline engines, often paired with API SP on modern oils.
- OEM approvals: Some brands require specific approvals (examples include VW 504.00/507.00, GM dexos1 Gen 2, MB 229.51, BMW Longlife, Toyota WS, etc.). Always verify compatibility with your vehicle’s badge and year.
- Viscosity grade: The two-digit, Y-axis numbers (e.g., 0W-20, 5W-30, 10W-40) indicate how the oil behaves at cold start and operating temperature. Use the grade recommended by the manufacturer and suitable for your climate.
- Label honesty: Look for “full synthetic,” “synthetic blend,” or “mineral” as descriptors, but prioritize the spec and viscosity over the marketing term.
By reading these specifications, you ensure the oil will protect your engine under the conditions it was designed for, while maintaining efficiency and emissions performance.
Practical tips for different engines
Engine design and usage patterns influence which oil is most appropriate. Here are scenarios to consider when choosing oil.
- Mild, non-turbo petrol engines in temperate climates: A conventional or synthetic-blend oil with a viscosity around 5W-30 or 10W-40 may suffice, following the manual.
- Modern turbocharged or high-performance petrol engines: Typically benefit from synthetic oils with low viscosity (0W-20 or 5W-30) to improve cold-start flow and reduce heat buildup.
- Cold climates: Oils with a lower cold-start viscosity (0W- or 5W-) improve starting, fuel efficiency, and protection during winter.
- Hot climates or heavy-duty driving: Higher second-number viscosities (40 or 50) may be appropriate, especially in high-load conditions; synthetic oils with robust oxidation resistance are often preferred.
- Older engines or high-mileage vehicles: High-mileage oils with seal conditioners can help reduce leaks and consumption, but ensure they meet OEM specs.
Always tailor these choices to what your car’s manufacturer prescribes and your actual driving environment.
Bottom line
The universal “best” oil does not exist. The safest and most effective choice is an oil that meets your vehicle’s specific viscosity and specification requirements and is suited to your climate and driving style. For most modern petrol engines, engines run best on a high-quality synthetic oil that bears API SP and ILSAC GF-6 approvals, in the viscosity grade recommended by the manufacturer. When in doubt, consult the owner's manual or a trusted mechanic and choose a reputable brand.
Summary
To select the best oil for a petrol engine, start with the carmaker’s recommendations, including viscosity and approvals. Consider climate and driving habits, then decide between conventional, synthetic, or synthetic blend. Read the bottle for API and OEM approvals, and ensure the chosen oil meets the required specifications. In short, compatibility with the engine’s specifications and operating conditions is the key to optimal protection and performance.
