The 2007 engine designs place new demands on lubricants. The new engines are expected to boost exhaust gas recirculation (EGR) rates from the current 13% to as high as 30%. EGR systems can cause a lot of soot, so the new oils require superior soot-dispersing capabilities.

New Engine Oils
Rising to the challenge, oil manufacturers have developed heavy duty engine oils (HDEOs) to comply with 07 low-emission hardware. The new oils are officially licensed API CJ-4. They better handle the higher soot levels that are expected, and help enable 2007 engines meet the EPA clean air standards. The increase in soot levels will be a result of the increased EGR flow. CJ-4 oils will protect emissions control devices, and will be more resistant to thermal breakdown.

Regulation Limits
The new oils will differ from past oils with the use of higher quality base stocks. These base stocks are naturally lower in sulphur content which will help protect the aftertreatment devices. The structure of the oils will be modified to accommodate certain chemical levels that have to be capped to meet the new EPA standards. The chemical constraints are designed to protect the exhaust aftertreatment devices. The new limits are as follows:

Oil Content – Limit
Ash – 1.0%
Phosphorus – 0.12%
Sulphur – 0.4%
Oil Volatility – 13%

The lower sulphur and phosphorus levels will protect the catalyst used in the aftertreatment device as well as decrease the ash content in CJ-4 oils. Ashless components will be used to replace the previous ash containing additives to ensure the protection of the engines against wear and deposits. The use of ULSD with a sulphur limit of 15 ppm maximum (as compared to the previous on-road low sulphur diesel specification of 500 ppm sulphur maximum) will significantly reduce the chances of catalyst poisoning in the aftertreatment device and lower the overall amount of ash collecting in the DPF system.

Now more than ever, purity is an issue and particulates and contaminants are an even bigger risk factor for next generation engines.

User Concerns
Users want to know how the CJ-4 oils will impact drain intervals and if the new oils will be backwards compatible. According to engine and oil manufacturers, CJ-4 oils will be backwards compatible. As a result, users have the choice to use one or two oils while transitioning fleets from old engines to new low emission engines. Fleet managers will be inclined to stock only one type of oil to avoid the costly mistake of using oil not recommended for their engine. One thing is for sure: each business will either have to observe a check process to ensure the correct oil is used or make the jump to CJ-4 for all of their engines new and old.

Drain intervals will depend on a number of factors, including OEM-recommended drain intervals and the nature of use (i.e. type of driving and loads). According to OEMs current drain intervals will not change for new engines using CJ-4 oils. Extended drains will still be possible with a robust oil analysis program in place.

Because of the required lower ash levels of CJ-4 oils, total base number (TBN) levels will also be reduced down to about 8 to 10 instead of the current 11 to 15. Reduced TBN means less acid neutralization capability, which theoretically would result in shorter drain intervals. However, ULSD fuel will compensate for the reduced TBN in CJ-4 oils. Less sulphur in the fuel will reduce oil stress, which will help extend drain intervals.

The use of ULSD fuel will result in cleaner combustion and less sulphuric acid produced in the engine. The lower levels of acid will extend the life of the TBN in the oil. If all other factors remain the same, oil drain intervals should be extended. It is expected that these two characteristics will cross each other out and the new oils will perform well with respect to oil drain interval.

The Cost Factor
The price of the new CJ-4 oils is one question that remains unanswered and will ultimately be determined by the marketplace.

There is a cost associated with the development of new technologies. Oil manufacturers invest a significant amount of resources each time a new HDEO standard is introduced. The 2007 regulation is no different; oil manufacturers have put a significant investment into the development of CJ-4 oils. The new oils have to pass approximately 25 tests, at a cost of around $25 million to the industry. The benefit of the rigorous CJ-4 tests for customers will be oil consistency and performance benefits, including improved soot management, less engine wear and longer engine life.

Will the new oils perform as promised by manufacturers? This and more will be discussed next week in the second and final installment of CJ-4 Oils Is the trucking industry prepared?