What type of oil is recommended for Cummins engines?
2 Answers
Cummins recommends using engine oil with specifications of 15W-40 CF4, CG4, CF4/SG, or CG4/SH. The type of oil should also be determined based on the engine's operating environment. If the ambient temperature is above -5°C, it is recommended to use 15W-40 CF4, CG4, CF4/SG, or CG4/SH-grade oil. If the ambient temperature is below -5°C, it is advised to use 10W-30 CF4, CG4, CF4/SG, or CG4/SH-grade oil. The viscosity of engine oil changes with temperature, so special attention should be paid to its performance under both low and high-temperature conditions. For example, in 5W-30 oil, the first number indicates low-temperature fluidity—5W means it can withstand temperatures as low as -30°C. The smaller this number, the better the low-temperature fluidity, ensuring smoother cold starts for the engine. The second number represents the oil's kinematic viscosity at 100°C. A higher number indicates better viscosity retention under high temperatures, which can be understood as better lubrication performance in high-temperature conditions. When selecting engine oil, keep the following considerations in mind: Choose oil based on the engine's requirements. There is no need to use overly advanced oil in engines with lower requirements, nor should lower-grade oil be used in engines with higher demands. It is advisable to opt for multi-grade oil whenever possible. Multi-grade oil offers benefits such as cost savings, extended lifespan, and high efficiency, providing better protection for the engine. Due to its characteristics, multi-grade oil may appear darker prematurely and exhibit lower oil pressure compared to conventional oil, both of which are normal phenomena.
The main oil viscosity grade used in Cummins engines is 15W-40, which meets API CJ-4 or CK-4 standards. I have extensive experience with this, having driven trucks for over a decade. There are slight variations between different engine series like ISX or B series, but the key is to choose certified oil to avoid wear caused by non-standard products. In northern regions during winter, you might switch to 10W-30, while 15W-40 suffices in summer. I use Mobil or Shell CJ-4 oil, changing it every 8,000 kilometers for worry-free operation and turbocharger protection. If you can't be bothered to check the manual, just ask your dealer directly - don't try to save money at the risk of damaging your engine.
