LUBRICATION GUIDE
API CK-4 vs CI-4: Diesel Engine Oil Categories Explained
By the PCG Technical Desk · Updated 27 September 2026
Quick answer: API CI-4 (introduced in 2002) and CI-4 Plus were written for engines with EGR. API CK-4 (introduced in December 2016) adds tougher requirements for oxidation, shear stability and aeration for modern low-emission engines. It is designed to be backward compatible with CJ-4, CI-4 Plus, CI-4 and CH-4 applications. FA-4 is a separate, lower-viscosity category that is not backward compatible.
What this means for your fleet
- Use the category your engine manual specifies. An oil meeting a newer backward-compatible category can generally be used where an older one is specified.
- Don't use FA-4 unless the engine maker permits it.
- BS-VI engines in India typically call for newer categories. Check the OEM manual.
Where SERVO grades fit (IOCL data sheets)
| Grade | IOCL-listed performance |
|---|---|
| Servo Pride TC 15W-40 | API CF-4 / SG, MB 228.1 |
| Servo Pride XL 15W-40 | API CH-4, MB 228.3, Cummins CES 20076, Volvo VDS-2 |
| Servo Premium CG-4 15W-40 | API CG-4, MB 228.3, Mack EO-M |
For CI-4 or CK-4 requirements, ask us for the current SERVO grade that carries that approval, with its latest data sheet.
Outside Karnataka? The technical information on this page applies anywhere in India. PCG Business Solutions supplies SERVO in seven Karnataka districts. If you are in another state, send us your requirement and we will point you to IndianOil's authorised channel for your area, or answer any technical question about the grade.
Recommended SERVO grades
FAQ
FAQs
API designed CK-4 to be backward compatible with CI-4 applications, so a CK-4 oil can generally be used where CI-4 is specified. Always check the engine maker's guidance.
