Why We Need Another Heavy-Duty Engine Oil–API CJ-4

A new diesel engine oil quality, called API CJ-4, will be introduced into North America on October 15. This oil will be the best performing heavy duty diesel engine oil that the industry has produced. However, customers may wonder why they should replace an oil like the current API CI-4 PLUS, which is doing an excellent job. The answer is the same as it has been for the last four category upgrades: a new emission standard is coming at us across North America. However, this new standard is aimed at the on-road operators. Off-road operators will be able to use API CI-4 PLUS oils for a few more years.

The illustration shows that the 2007 on-road emission standards are significantly tighter than the 2004 standard and, in fact, diesel engines cannot burn fuel cleanly enough to meet the new particulate matter (PM) level that will be required. To achieve this level, an exhaust treatment device call a diesel particulate filter (DPF) will be used by all Class 8 diesel engines to filter particulate matter out of the exhaust. The other critical emission–nitrogen oxides (NOx)–will be achieved by engine combustion at the new 2007 level.

For the DPF to be successful in limiting the particulates to the new legal level, two other conditions must be met. First, the sulphur level in the diesel fuel must be reduced to 15 ppm; the new fuel is called ultra-low-sulphur diesel (ULSD). Second, the engine must operate on API CJ-4 quality oil. API CJ-4 engine oils have compositional limits that restrict the amount of sulphated ash (metals), sulphur and phosphorus that can be in the oil. The use of ULSD and API CJ-4 oil will allow the DPFs to operate successfully and the 2007-emission-calibrated engines to meet their design targets. Use of the old API CI-4 PLUS oils in 2007-emission-calibrated engines will cause the DPFs to plug with solids prematurely and will required expensive servicing or replacement.

These changes will result in better protection for the environment through lower emissions from the engines. But there is more good news. All engines are going to be better protected by the CJ-4 oils. This new category is designed to be superior in performance to API CI-4 PLUS oils for oil consumption, valve train wear, control of soot-induced viscosity increase, piston deposits and oxidation control. So, even for engines that predate 2007 emission standards and do not have DPFs, these oils are very good news since they will bring added protection and are designed to give longer engine life.

These performance improvements were the result of the hard work of the industry committees which brought four new engine tests into the approval process (two Cummins engines, one Mack and one Caterpillar). There are five other existing engine tests that are used in the approval program for a total of nine engine tests for approving an oil against the API CJ-4 quality standard. API CJ-4 has the most engine tests and is the most expensive API category to approve of any engine oil category to date.

However, there is one drawback: the new API CJ-4 formulations with compositional restrictions and the larger number of engine tests required to deliver quality improvements will result in increased costs.

Off-road engines do not require DPFs since they operate under different emission standards than on-road engines and are currently more like the 2004 on-road standards. The on- and off-road standards are expected to merge in 2010 when a common product for these two marketplaces will again make sense. However, for the next four years, API CI-4 PLUS quality oils will likely satisfy the off-road customer very well and, in fact, these oils have performed excellently in the off-road marketplace. Imperial Oil’s existing XD-3 Extra 15W-40 and 10W-30 will be left at their current quality levels (API CI-4 PLUS and API CI-4) for customers who may want to stay with a product that has served them well and meets the needs of their equipment.

For the 2007-emission-controlled engines, Imperial Oil will introduce a new product called Esso XD-3 Extra CJ-4 15W-40, and will upgrade Delvac 1300 Super 15W-40 and 10W-30 to API CJ-4 quality. This will meet the needs of on-road customers who require API CJ-4 oils for their 2007-emission-controlled engines, or on- and off-road customers who prefer the higher quality level that our API CJ-4 delivers.

Clinton R. Smith is a technical advisor at Imperial Oil and can be contacted at clint.r.smith@esso.ca.