What is Engine Oil Grade?
An engine oil grade refers to the classification of engine oils based on their viscosity, performance level, and temperature range. The grade indicates how thick or thin the oil is at different temperatures, which plays a crucial role in engine protection and performance. The Society of Automotive Engineers (SAE) sets the viscosity grading system, while organizations like API (American Petroleum Institute), ACEA (European Automobile Manufacturers Association), and JASO (Japanese Automotive Standards Organization) provide further specifications based on oil performance.
Engine Oil viscocity grades
Before the hyphen: The number before the hyphen indicates the oil’s viscosity at low temperatures, such as when the engine is cold.
After the hyphen: The number after the hyphen indicates the oil’s viscosity at normal operating temperatures, which is around 100 degrees Celsius
Here are some common engine oil grades and their uses:
0W-20: A thin oil that performs well at high temperatures and is good for maximum fuel economy
0W-30: A thin oil that flows well when cold and performs well at high temperatures
0W-40: An oil that performs well at both cold starts and high temperatures
5W-30: A commonly used oil that handles a wide range of temperatures
5W-40: A fully synthetic oil that provides stable protection at both cold starts and high temperatures
10W-40: An oil that’s suitable for engines that operate at both low and high temperatures
The Society of Automotive Engineers (SAE) has developed a numerical coding system to grade engine oils
Here is a summary of common engine oil grades, their viscosity, and key features to help you make an informed choice:
| Oil Grade | Viscosity | Use/Ideal For | Key Features |
|---|---|---|---|
| 5W-30 | Multi-viscosity | Modern engines in moderate climates | Best for fuel economy, effective in both cold and warm temperatures. |
| 10W-40 | Multi-viscosity | Vehicles in warmer climates or older engines | Better protection at higher temperatures, good for high-mileage engines. |
| 20W-50 | Multi-viscosity | Older or high-performance engines | Thicker oil for better protection in high-performance or older engines. |
| API SN | Performance-based | Gasoline engines | Excellent protection against wear, high-temperature stability, and sludge control. |
| API CJ-4 | Performance-based | Diesel engines with emission systems | Designed for modern diesel engines, including those with DPF. |
| ACEA A3/B3 | European standard | High-performance gasoline and diesel engines | Protection against wear and high-temperature degradation. |
| ACEA C3 | Low SAPS | Modern cars with emission control systems (e.g., DPF) | Suitable for emission systems, reduces particulate filter clogging. |
| JASO MA | Friction-based (wet clutch) | Motorcycles with wet clutch systems | Proper friction properties to prevent clutch slippage. |
| JASO MB | Friction-based (lower) | Scooters or motorcycles with automatic transmissions | Low friction for automatic transmission systems. |
Common Engine Oil Grades
- SAE Viscosity Grades
- The most common viscosity grades you’ll encounter are represented by numbers like 5W-30, 10W-40, and 20W-50. The “W” stands for winter, and the numbers before and after it represent the oil’s performance in cold and high temperatures, respectively.
- 5W-30: This oil performs well in both cold and high temperatures, offering good fuel economy.
- 10W-40: Ideal for higher temperature ranges, providing better protection in hot climates.
- 20W-50: Typically used in high-performance or older engines where thicker oil is required.
- The most common viscosity grades you’ll encounter are represented by numbers like 5W-30, 10W-40, and 20W-50. The “W” stands for winter, and the numbers before and after it represent the oil’s performance in cold and high temperatures, respectively.
- API Service Categories
- The API service category indicates the performance level of the oil. The categories are often labeled with “S” for gasoline engines (e.g., API SN, API SL) and “C” for diesel engines (e.g., API CK-4, API CJ-4).
- API SN: Latest standard for gasoline engines, offering excellent protection against wear, sludge, and high-temperature degradation.
- API CJ-4: Designed for modern diesel engines, particularly those with emission control systems.
- The API service category indicates the performance level of the oil. The categories are often labeled with “S” for gasoline engines (e.g., API SN, API SL) and “C” for diesel engines (e.g., API CK-4, API CJ-4).
- ACEA (European) Standards
- ACEA grades focus on the oil’s ability to protect and maintain engine performance, with specific categories for passenger cars (A/B), low SAPS (C), and heavy-duty diesel engines (E).
- ACEA A3/B3: High-performance oils for gasoline and diesel engines.
- ACEA C3: Suitable for modern vehicles with emission systems like DPF (Diesel Particulate Filters).
- ACEA E9: Heavy-duty oils for diesel engines with advanced emission systems.
- ACEA grades focus on the oil’s ability to protect and maintain engine performance, with specific categories for passenger cars (A/B), low SAPS (C), and heavy-duty diesel engines (E).
- JASO Standards
- JASO oil grades are particularly important for motorcycles. They specify the oil’s friction properties, which are crucial for clutch performance in wet clutch systems.
- JASO MA: For motorcycles with wet clutches.
- JASO MB: For scooters and motorcycles with automatic transmissions.
- JASO MA2 oils offer increased frictional performance, for high clutch control.
- JASO oil grades are particularly important for motorcycles. They specify the oil’s friction properties, which are crucial for clutch performance in wet clutch systems.
How to Choose the Right Engine Oil?
Choosing the correct engine oil depends on several factors:
- Vehicle type: Whether your vehicle is a passenger car, commercial vehicle, or motorcycle.
- Manufacturer recommendations: Always check your owner’s manual for the recommended oil grade.
- Climate conditions: Consider the temperature range in your area, as oils with different viscosities perform better in specific temperatures.
- Engine age and performance needs: Older engines may require thicker oils for better protection, while newer engines may benefit from oils with better fuel economy properties.