Countertalk: Knowledge Building: 10 Must Know Facts About New Diesel Engine Oil

1. The American Petroleum Institute (API) ushered in the CJ-4 Standard in October 1996, but it is still finding its way into more common usage as the fleet of vehicles on the road is gradually replaced.

2. Motor oils meeting this standard are specifically designed in cooperation with manufacturers for use in high-speed four-stroke cycle diesel engines designed to meet 2007 model year on-highway exhaust emission standards, as well as standards for previous model years.

3. New emission standards for heavy-duty engines will be phased in between 2007 and 2010. Engines meeting these new standards will be equipped with advanced emission control technologies, including diesel particulate filters (DPF), and in most cases exhaust gas recirculation (EGR). The new API CJ-4 performance category was developed to address both the unique needs of these new engines and to protect older engines, while enhancing the life of the emission control system as required for regulatory compliance.

4. Its use is not optional for the new generation of low-emissions diesel engines, just as ultra low sulphur diesel fuel is not optional. Optimum protection is provided for control of catalyst poisoning, particulate filter blocking, engine wear, piston deposits, low- and high-temperature stability, soot handling properties, oxidative thickening, foaming, and viscosity loss due to shear.

5. CJ-4 oils are not just a little better than the CI-4 and CI-4 Plus lubricants that precede them; they represent a significant change in technology. CJ-4 oils have additive systems specially designed to improve the protection of both the engine power system and advanced emissions control systems like DPFs.

6. Use of these new oils will help maintain the life of the emission control system as required for regulatory compliance. API CJ-4 oils are formulated for improved wear protection, deposit and oil consumption control, soot-related viscosity control, prevention of viscosity loss from shearing, used oil low-temperature pumpability, and protection from thermal and oxidative breakdown when compared to previous API performance categories.

7. Drain intervals for the CJ-4 oils may differ considerably from previous experience; users should consult their manufacturer’s recommended schedule.

8. Some operators have an oil analysis program in place and previous analysis does not yield accurate results. API CJ-4 oils may have a different fresh oil chemical profile from previous oils, because one of the key requirements of the API CJ-4 category is the setting of maximum limits on the phosphorus, sulphur, and sulphated ash content of oils.

9. Some customers may wonder if CJ-4 oils can be used in older engines designed for CI-4 and CI-4 Plus. Older engines can use the new CJ-4 spec lubricant.

10. The CJ-4 motor oils were designed to work with the ’07 low-emissions engines, which also required ultra-low sulphur diesel containing no more than 15 ppm of sulphur. While the oils can work well in engines designed for use with higher sulphur content, use of these engines with higher-sulphur concentrations can put particulate filters and other emissions components at risk.

Always advise customers with ’07 engines that it is worth any additional lubricant and fuel costs they might incur to help preserve expensive emissions components.