Engine oil must have sulfate ash levels less than 1.0 weight percent. Oil meeting this requirement is labeled as which classification?

Engine oil must have sulfate ash levels less than 1.0 weight percent. Oil meeting this requirement is labeled as which classification?

• A. CJ-4 Oil
• B. CJ-4 Plus Oil
• C. CI-4 Oil
• D. CK-4 Oil

Answer: (A)

Sulfated ash is a measure of metal-containing additives that can form deposits in diesel engines, especially affecting exhaust after-treatment like diesel particulate filters. Oils labeled for CJ-4 are formulated to keep this ash under 1.0 weight percent, ensuring compatibility with modern high-speed diesel engines and their after-treatment systems. That’s why this oil classification is the one specified for meeting the <1.0% ash requirement. The other designations refer to different engine generations or variants with different additive and performance specs, not the specific low-ash criterion described.

Sulfated ash is a measure of metal-containing additives that can form deposits in diesel engines, especially affecting exhaust after-treatment like diesel particulate filters. Oils labeled for CJ-4 are formulated to keep this ash under 1.0 weight percent, ensuring compatibility with modern high-speed diesel engines and their after-treatment systems. That’s why this oil classification is the one specified for meeting the <1.0% ash requirement. The other designations refer to different engine generations or variants with different additive and performance specs, not the specific low-ash criterion described.