Low Ash Lube Oil
CJ-4 is the American Petroleum Institute (API) lube oil specification for engines using exhaust aftertreatment such as a Diesel Particulate Filter (DPF) and cooled Exhaust Gas Recirculation (EGR). Commonly known as “low ash” oil, it is more resistant to heat and leaves lower amounts of ash deposits when it does burn off during the combustion process. The lower ash content of the oil enables the DPF to reach the EPA mandated 4,500 hour ash cleaning service interval for engines above 174 hp (130 kW). However, Cummins expects to extend this service interval to 5,000 hours.
In Europe, the equivalent specification to CJ-4 low ash oil is ACEA E9, which was also introduced specifically for engines using exhaust aftertreatment. CJ-4 was first introduced for use with EPA 2007 on- road engines and is now the industry recommended specification for Tier 4 Interim engines, as is ACEA E9 in Europe for Stage IIIB engines.
So Why The Oil Spec Upgrade? Tier 3 off-road engines in North America can currently use the API CH-4 spec introduced in 1998 or the CI-4 spec introduced in 2002. However, using EGR and a DPF significantly increases demands on lube oil performance. Here’s why:
EGR: by operating at elevated temperatures EGR creates additional demands on the lube oil. Recirculating the exhaust gas results in higher amounts of soot (the hard carbon particles in the exhaust) for the lube oil to hold in suspension. CJ-4 and E9 oil are formulated to deal with these higher soot loadings and prevent premature engine wear.
DPF: small amounts of the engine oil are consumed by the combustion process, this results in the formation of incombustible ash. This ash is formed from the base stock and trace minerals found in the oil additive pack. The DPF traps the ash in the same way it traps particulate matter (PM). However, the ash remains incombustible in the DPF - unlike the PM which is oxidized. CJ-4 and E9 low ash oil help extend the ash cleaning interval to its maximum level, as they contain a lower level of trace minerals within the additive pack to generate less ash. The CI-4 spec introduced in 2002 does not have a low ash formulation.
The new CJ-4 is backwards compatible so it can also be used in engines meeting Tier 3/Stage IIIA and other previous emissions regulation standards as long as the engine is also operating with ultra-low sulfur diesel ULSD) fuel (15 ppm or less sulfur content).
Cummins highly recommends the use of a high quality heavy-duty engine oil, such as Valvoline Premium Blue, which meets or exceeds the API performance classification CJ-4. The CJ-4 classification indicates that the lube oil has been specifically designed to work with both cooled EGR and exhaust aftertreatment when using Ultra-Low Sulfur Diesel of 15 ppm sulfur content.
Will oil change intervals stay the same? Yes. Oil change intervals will remain the same when using low ash lube oil.