What are the quality grades of diesel engine oil?

[Makayla]

Diesel engine oil quality grades include: CA, CB, CC, CD, CE, CF, CF4, CG4, CH4, CI4, CJ4. The further back the letter is in the alphabet, the higher the oil quality grade, so the highest grade is CJ4. Currently in China, CF4 is the main grade for diesel engine oils. CF4 oil performs better than CF in terms of fuel consumption and piston deposit control, making it suitable for diesel engines using high-sulfur content diesel, high-speed direct injection diesel engines, and heavy-duty diesel engines. Moreover, the service life of CF4 is twice that of CD. When selecting engine oil for diesel vehicles, in addition to choosing the quality grade, the viscosity grade should not be overlooked. The appropriate viscosity can be selected based on factors such as local temperature conditions, the actual situation of the vehicle, and the viscosity recommended by the engine model.

[DiEmmett]

The quality grade of diesel engine oil mainly refers to the API classification. As an old truck driver with twenty years of experience, I've seen many changes. Back in the day, we used CA and CB grade oils for old engines—simple, rough, but durable. Nowadays, engines are much more sophisticated, and the grades have evolved to CI-4, CJ-4, and the latest CK-4, which indicate the quality level of the oil. API is an international standard, and the higher the number, the better the oil's anti-wear, cleaning, and thermal stability performance. For example, CK-4 is specifically designed for high-efficiency emissions and is suitable for long-haul trucks, protecting engine components and reducing carbon buildup. Choosing the right oil depends on the vehicle manual's recommendations—using the wrong grade can lead to engine overheating or increased fuel consumption, a mistake I often see new drivers make. Climate also matters; lower viscosity grades work better in winter for smoother operation. In short, older grades meet basic needs, while newer ones combine environmental considerations and performance advancements, making the engine more powerful.

[VanessaLynn]

As a mechanic who works on diesel vehicles all day, let me explain these classifications from a technical perspective. The API diesel oil quality ratings start from CA and progress up to CK-4 and FA-4, with each grade designed for different operating conditions. For example, CF-4 is suitable for heavy-duty trucks with excellent high-temperature oxidation resistance; CJ-4 incorporates low-ash additives to reduce exhaust emissions; CK-4 is the latest standard, improving fuel economy while protecting DPF systems. These classifications are primarily determined by API standard tests evaluating oil viscosity, anti-wear performance, and detergency. When selecting oil, consider engine type and operating conditions – long-haul trucks should use CK-4 for sustained operation stability, while urban vehicles may only require CH-4. I also recommend that vehicle owners learn to read oil labels and manuals to avoid using lower-grade oils that could lead to major overhauls. Remember, regular oil changes combined with proper grade selection can significantly extend engine life.

[RonanAnn]

After buying a diesel SUV, I gradually learned about engine oil quality grades. Simply put, API classifications like CF, CG-4 up to CK-4 indicate oil grades, with higher numbers representing better performance. CF grade suits older vehicles but isn't adequate for newer models, while CK-4 supports high-compression engines with wear protection. When choosing, consider your vehicle's age and manual recommendations—don't cheap out with low-grade oil. Upgrading grades might even save some fuel costs and extend maintenance intervals. Prioritize ease of use and keep it simple.