What are the types of diesel engine oil?
3 Answers
In the API quality classification system, the C series represents diesel engine oils. There are various grades of diesel engine oil, which can be roughly categorized into the following: CA, CB, CC, CD, CE, CF, CF-4, CG-4, CH-4, CI-4, CJ-4, etc. These letters represent different meanings. According to the alphabetical order, the later the letter appears, the higher the quality grade of the oil. Therefore, it is clear that CJ-4 is the highest grade for diesel engines. Below is some relevant information: CD-grade oil: General diesel engines can use CD-grade oil, while turbocharged diesel engines require higher-quality oil. The '-4' indicates that the oil is suitable for four-stroke diesel engines. Additionally, some diesel engine oils are labeled as SC, indicating that they can be used in both gasoline and diesel engines. CF-4: In China, CF-4 is currently the main grade for diesel engine oils. CF-4 oil performs better than CF in terms of fuel consumption and piston deposit control, making it suitable for diesel engines using high-sulfur diesel, high-speed direct injection diesel engines, and heavy-duty diesel engines. Moreover, the service life of CF-4 is twice that of CD. In terms of diesel engine oil brands, Mobil, Castrol, and Shell all have corresponding products. Generally, light-duty vehicles such as pickups or diesel SUVs can choose dual-purpose oils suitable for both diesel and gasoline engines.
I've been driving long-haul trucks for over a decade, and choosing the wrong diesel engine oil can be disastrous. The most common is the SAE viscosity grade. For example, 10W-30 is suitable for cold starts in northern winters, while 15W-40 is widely used in the south for stronger protection. The API grade currently popular is CK-4, which offers good cleaning performance and fuel efficiency. Older vehicles can still use CI-4 reliably. Never buy blindly—wrong choices can easily damage the engine. For instance, oil that's too viscous makes cold starts difficult in winter, while oil that's too thin can lead to overheating in summer. We drivers usually refer to the vehicle manual for recommended specifications, with oil change intervals between 7,000 to 10,000 kilometers—cost-effective and worry-free. If you drive more on mountain roads, a thicker oil is needed for better wear resistance. In short, adapting to seasons and road conditions is the most reliable approach.
Working in an auto repair shop, I often help vehicle owners choose diesel engine oil. The selection mainly depends on SAE viscosity and API grade: SAE ratings like 15W-40 indicate 15 for low-temperature fluidity and 40 for high-temperature viscosity, with higher numbers after 'W' meaning better heat resistance; API standards like CK-4 represent current specifications with better pollution prevention and environmental protection. Light trucks should use thinner 10W-30 oil for quicker acceleration, while heavy-duty trucks require thicker 20W-50 oil for better engine protection. Be careful not to mix different brands of oil to avoid chemical reactions that could damage lubrication. I recommend checking oil levels every 5,000 kilometers and using oil that meets the manual's certification to extend engine life, save money, and prevent malfunctions.
