What is the difference between CI-4 and CH-4 diesel engine oils?

CF-4, CH-4, CI-4, and CJ-4 are quality grades for diesel engine oils. For example, CH-4 indicates a CH-grade quality level, with the “4” signifying it is for four-stroke engines. Currently, CF-4 and CH-4 are the most commonly encountered grades.
CF-4 is designed for high-speed direct-injection diesel engines, outperforming CF in fuel economy and piston deposits. It is suitable for high-sulfur diesel fuel and particularly recommended for heavy-duty trucks. Compared to CF, CF-4 offers more comprehensive performance, and its oil change interval is twice that of CD.
Differences between CF-4, CH-4, and CI-4 diesel engine oils
CF-4: Introduced in 1990, suitable for high-speed, four-stroke, naturally aspirated or turbocharged diesel engines. Replaces CD and CE oil grades.
CH-4: Introduced in 1998, suitable for high-speed four-stroke diesel engines meeting 1998 U.S. emissions standards and using fuel with sulfur content below 0.5%. Can replace CD, CF-4, and CG-4 oil grades.
CI-4: Introduced in 2002, suitable for high-speed four-stroke diesel engines meeting the 2004 U.S. emissions standards. For vehicles equipped with Exhaust Gas Recirculation (EGR) systems, CI-4 oil effectively maintains engine stability and is suitable for use with fuel containing sulfur content below 0.5%. Can replace CD, CE, CF-4, CG-4, and CH-4 oil grades.
CI-4 diesel oil extends oil change intervals beyond CH-4 specifications.
1. Enhanced oil stability and oxidation resistance
2. Reduced evaporation loss to lower oil consumption
3. Improved TBN and retention through advanced formulations
4. Enhanced cleaning and dispersancy—enables the oil to dissolve greater amounts of combustion and oxidation byproducts without forming sludge, carbon deposits, or varnish.
Selection Principles for Diesel Engine Oil: Ensuring both reliable performance and good economy presents a challenge for users. First, refer to the vehicle manufacturer's recommendations. For users, the simplest approach is to follow the principle of “choosing the higher specification rather than the lower one.”