How to Identify Engine Oil Grade?
4 Answers
To identify the engine oil grade, note that oil grades range from SA to SN, with this designation indicating the oil quality. The further the letter after 'S' is in the alphabet, the higher the oil quality. Engine oil grades are categorized as follows: 1. 'S' stands for gasoline engine oil, and 'L' represents the grade. The later the letter, the higher the oil grade. 2. 'C' stands for diesel engine oil, and 'F' represents the grade. Similarly, the later the letter, the higher the oil grade. The functions of engine oil include: 1. Reducing friction and high temperatures; 2. Minimizing gas leakage and preventing contamination from external pollutants; 3. Protecting against contact with water, air, and acidic harmful gases; 4. Cushioning the pressure rise in the engine cylinder; 5. Cleaning dirt generated on the working surfaces of components.
I always pay special attention to grade identification when changing the engine oil for my beloved car. The most straightforward method is to check the label on the front of the oil container—you'll see SAE viscosity codes like 5W-30 and API quality grade markings such as SP. These alphanumeric combinations actually represent the oil's low-temperature fluidity, high-temperature viscosity, and environmental standards. For example, my old German car requires 0W-40, while Japanese cars are more suited to 5W-30. Before maintenance, I recommend checking the vehicle manual to confirm the manufacturer's requirements. When purchasing oil, remember to verify the label on the container to avoid being tricked by sellers into using lower-grade oil.
Last time I went to the auto parts market to buy engine oil, I noticed that the grade markings are positioned differently on various packaging. For metal cans, it's usually laser-etched on the side, while plastic containers have large SN/SP labels printed directly on the front. Focus on two sets of codes: the SAE viscosity grade with the W alphanumeric combination, and the two-letter API classification. Additionally, for European cars, look for the ACEA A3/B4 designation. If the packaging is worn and unreadable, you can scratch off the anti-counterfeit coating and scan the QR code with the official app to verify parameters, which is more reliable.
As a car mechanic with ten years of experience, here are some practical tips: First, check the circular certification mark on the engine oil packaging. The latest standard is indicated by words like 'API SN PLUS' in the middle. Then, refer to the specification table on the back of the packaging—legitimate products will fully list the grade parameters. For opened engine oil, you can pour a small amount onto white paper to observe its color. Full synthetic oil appears translucent amber, while mineral oil is darker yellow with poorer fluidity. However, color alone cannot accurately determine the grade, so it's best to keep the oil container and take photos for records.
