Which engine oil type is best?

There isn’t a single “best” engine oil for every car. The right choice depends on your engine design, climate, and driving habits. For most modern vehicles, synthetic or synthetic-blend oils that meet the manufacturer’s specifications are preferred, typically in viscosities such as 0W-20 or 5W-30. Always start with the owner's manual and the oil specification on the label.

What “best” means for your vehicle

In automotive maintenance, “best” means the oil that protects the engine under your typical conditions while meeting the maker’s specifications. Factors include the engine type (turbocharged, direct-injected, or naturally aspirated), warranty requirements, climate, and how you drive (short trips, towing, or high-mileage use). The recommendation is often to follow the manufacturer’s specification rather than chasing the newest trend.

Common engine oil types

Below is a quick overview of the main oil categories you’ll encounter. Each type has its own advantages and tradeoffs, and the best choice depends on your vehicle’s needs and budget.

• Conventional (mineral) oil: Basic protection and lowest cost, suitable for older engines with calm driving patterns. Needs more frequent changes and may not perform as well under extreme heat or cold.


• Synthetic oil (full synthetic): Superior oxidation resistance, better flow at cold temperatures, and stronger protection at high temperatures. Longer drain intervals and higher price. Frequently recommended for modern, high-performance, or turbocharged engines.


• Synthetic blend (semi-synthetic): A middle-ground option that offers better protection than conventional at a lower cost than full synthetic. Good for moderate driving and climate conditions.


• High-mileage oil: Formulated with additives to help condition aging seals and reduce oil consumption in engines with 75,000 miles (120,000 km) or more. Not a replacement for proper maintenance but can be beneficial for older engines.

Choosing among these depends on the car’s requirements and your budget. While conventional oil can be adequate for some older or low-demand engines, most modern vehicles perform best with synthetic or synthetic-blend oils that meet the official specifications.

Viscosity and performance ratings you should know

Viscosity describes how thick or thin the oil is at a given temperature. Most modern cars specify a multi-grade viscosity (for example, 0W-20, 5W-30). The left number with a “W” indicates cold-temperature flow; the right number indicates hot-temperature protection. Here are common patterns and when they tend to be used.

• 0W-20 or 0W-30: Common in many new passenger cars and hybrids for improved cold-start protection and fuel efficiency. Follow the manual’s advice for climate and engine type.


• 5W-30: A versatile, widely used option suitable for a broad range of climates and engines, including many mid-size cars and SUVs.


• 5W-40, 10W-30: Used in hotter climates, older engines, or performance applications where higher hot-temperature protection is beneficial.

Always choose the viscosity specified by your manufacturer. Using a different oil grade can affect protection, fuel economy, and warranty coverage.

Oil specifications and classifications to look for

Oil products carry performance specifications from several organizations. Modern engines typically require oils that meet both API and ILSAC standards, and some European models require ACEA specifications. Here’s what to look for when reading the label.

• API SP: The current gasoline-engine performance level, offering enhanced protection and detergency compared with earlier API categories.


• ILSAC GF-6 (GF-6A/GF-6B): The latest class for gasoline engines, focusing on improved protection, efficiency, and compatibility with a wide range of engines. Oils labeled SP often carry GF-6 compatibility.


• ACEA (European standards): Required for many European-market vehicles and some high-performance or specialty engines. Some oils carry both API/ILSAC and ACEA designations.

In the United States, many cars can be certified with API SP/ILSAC GF-6 oils, but always verify what your manual specifies. If you drive a European-brand vehicle or a high-performance model, ACEA-rated oils may be necessary.

How to decide the best oil for your car

Use these steps to pick the right oil for your vehicle and conditions. This guide helps translate manual recommendations into real-world choices.

1. Check the owner’s manual for the exact viscosity and specification (for example, 0W-20 API SP GF-6 or 5W-30 API SP GF-6).


2. Consider your climate and driving patterns (frequent short trips, heavy towing, extreme heat or cold) and choose an oil that maintains protection under those conditions.


3. Assess engine mileage and condition. High-mileage engines can benefit from HM oils, but verify compatibility with the warranty and the engine’s needs.


4. Choose a reputable brand whose product explicitly meets the required API/ILSAC/ACEA specifications. Using a lower-spec oil can void warranties or reduce protection.


5. Follow the recommended change intervals, using the oil life monitoring system if equipped, and adjust if you switch from conventional to synthetic or vice versa.

Following these steps helps ensure you select an oil that protects your engine, preserves fuel economy, and aligns with maintenance schedules.

Bottom line

The “best” engine oil is the one that matches your vehicle’s explicit specifications and your driving environment. For most modern engines, synthetic or synthetic-blend oils that meet API SP and ILSAC GF-6 (or ACEA where applicable) are a solid default, especially when paired with the recommended viscosity. Always prioritize the manufacturer’s guidance in the owner’s manual and consider your climate, mileage, and driving style when making a final choice.

Summary

Choosing the best engine oil isn’t about chasing a single “superior” type; it’s about compatibility with your engine and conditions. Use the manual as your north star, select a viscosity that suits your climate and driving habits, and opt for synthetic or synthetic-blend oils that meet current API/ILSAC/ACEA specifications when recommended. Regular changes with the correct oil help protect engine life, maintain efficiency, and support warranty terms.

What happens if I put 5W-30 instead of 5W-20?

The 5W-20, however, will remain a little thinner once you reach operating temperature to help improve fuel economy and flow fast enough to fill the tight tolerances in the engine. Using 5W-30 instead can reduce fuel economy and impede flow throughout the engine.

Which engine oil is better, 5W-30 or 5W-40?

Neither 5W-30 nor 5W-40 is inherently better; the best choice depends on your vehicle, climate, and driving habits. Generally, use 5W-30 for better fuel economy in moderate climates, while 5W-40 is better for high-heat protection, heavy loads, or older engines. Always check your vehicle's owner's manual or the oil fill cap for the manufacturer's specific recommendation. 
You can watch this video to learn about the difference between 5W-30 and 5W-40 engine oil: 52sHonest Mechanic ColoradoYouTube · Jan 13, 2024
Choose 5W-30 if

• You want slightly better fuel efficiency. 
• You drive in a colder climate where the oil needs to flow easily on cold starts. 
• Your vehicle manufacturer recommends it for a modern gasoline engine. 

Choose 5W-40 if

• You frequently tow heavy loads or drive in extreme heat. 
• You have an older, high-mileage engine that may benefit from thicker oil to maintain pressure and reduce wear. 
• Your vehicle's manufacturer specifies it, especially for many diesel engines. 

How to choose

• Check the manual: This is the most important step. Your vehicle manufacturer's recommendation is the definitive guide for your engine's specific needs. 
• Consider your climate: Use 5W-30 for cooler climates and 5W-40 for hotter climates where the engine operates under more stress. 
• Evaluate your driving style: If you do frequent heavy-duty work, like towing, choose the oil that provides more high-temperature protection, which is 5W-40. 

This video explains the difference between 5W-30 and 5W-40 engine oil in more detail: 1mCar ExpertlyYouTube · Nov 2, 2025

Which is better, 5W30 or 10W30 oil?

No, one is not inherently better than the other; the choice between 5W-30 and 10W-30 depends on your climate and vehicle, with 5W-30 being better for cold weather starts and 10W-30 acceptable for consistently warm climates. When cold, 5W-30 flows more easily than 10W-30, offering better protection during cold starts because the "5W" rating indicates a lower viscosity in cold temperatures. At normal operating temperatures, both oils have the same "30" weight and thickness. 
When to use 5W-30

• Cold climates: This is the better choice if your region experiences cold winters or temperatures frequently drop below freezing. 
• Frequent cold starts: 5W-30 flows faster in cold weather, getting to vital engine components sooner during startup and reducing wear. 
• General use: Because it handles cold starts well and still performs in heat, 5W-30 is a versatile and safe bet for many climates. 

When to use 10W-30

• Consistently warm climates: If your area rarely gets below freezing, 10W-30 works just as effectively and may be sufficient. 
• If your manual recommends it: Always check your owner's manual first to see what viscosity your engine is designed for. 

Key takeaway

• Check your owner's manual: The best oil is the one your vehicle's manufacturer recommends for your specific engine. 
• Consider the temperature: If you live in a region with cold winters, choose 5W-30 for better cold-start protection. 
• They are the same when hot: Both oils are the same "30 weight" when the engine reaches normal operating temperature. 

Is it better to use synthetic oil or regular oil?

Yes, synthetic oil is generally better than conventional oil because it offers superior engine protection, performs better in extreme temperatures, and lasts longer, often allowing for extended oil change intervals. While synthetic oil is more expensive upfront, it can lead to lower overall maintenance costs and a longer-lasting engine. 
Benefits of synthetic oil

• Better engine protection: Synthetic oils have a more uniform molecular structure with fewer impurities, which reduces friction and wear, particularly in high-performance or heavy-duty applications. They also contain better cleaning additives to prevent sludge buildup. 
• Improved performance in extreme temperatures: Synthetics resist thickening in cold weather and breaking down in heat, providing reliable lubrication during cold starts and under high-load conditions. 
• Longer drain intervals: Synthetic oil maintains its viscosity and protective properties for a longer period, allowing for fewer and more spread-out oil changes. 
• Enhanced fuel efficiency: By reducing friction, synthetic oil can help improve horsepower and gas mileage. 
• Better for certain vehicles: It is recommended for high-performance engines, turbocharged engines, and vehicles that frequently tow or are driven in extreme climates. 

Drawbacks of synthetic oil

• Higher initial cost: Synthetic oil is more expensive per quart than conventional oil. 
• Potential incompatibility: Mixing synthetic and conventional oils is not recommended as it can compromise the benefits of the synthetic oil blend.