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Maintenance/Management: Everything oil is new again

May 28, 2009 |

It’s been a busy four years for the makers of heavy-duty on-road diesel engines and no less so for the producers of lube oils for these engines. Both groups have been scrambling to meet the latest round of deadlines imposed by the Environmental Protection Agency, which kick in January 1.

All on-highway diesel truck engines manufacturered from that day forward will have to emit fewer emissions and these new engines will require a new lube oil.

The good news is that the operational impact of these regulations on contractors has been minimal for the most part. The new engines are more expensive, but they’ve also become better and more efficient. The only change contractors and fleet managers have to make is in their preventive maintenance and the type of lube oil they use.

CJ-4 is not a jeep
The official spec for this new oil is the American Petroleum Institute CJ-4 category. (The CJ-4 name has nothing to do with Chrysler’s ever-popular Jeep. It’s just the next extension of a series of API specs – from CH-4 to CI-4, then CI-4+ and now CJ-4.)

The new oils have lower levels of phosphorous, ash and sulfur – additives that, if used in the 2007 engines, would increase maintenance and lower the performance of the exhaust aftertreament devices (diesel particulate filters and diesel oxidation catalysts) these engines need to produce cleaner exhaust. The new oils also have higher oxidation stability (resistance to breakdown in high heat situations) and soot dispersant capabilities – two conditions that get more severe in the new engines.

“Ash can plug up the diesel particulate filter, and when it is plugged up for a period of time it can cause back pressure, which has a detrimental effect on the whole engine,” says Reginald Dias, director, commercial products, ConocoPhillips Lubricants, Conoco brand. “The high levels of phosphorous and sulfur could have a negative effect or deactivate the catalyst in an oxidation catalyst. These aftertreatment devices are supposed to be warranted for 150,000 miles, but when you have higher ash, phosphorous or sulfur levels, that warranty could be voided,” he says.

How much it will cost to clean a DPF or oxidation catalyst has not been clearly established yet. Dan Arcy, technical manager for Shell Lubricants, estimates it may run from $300 to $500, not including a half day or so of downtime. How much more frequently you would have to clean the aftertreatment is likewise uncertain. A likely scenario is that if you were getting 150,000 miles between cleanups with the CJ-4 oil at 1-percent ash and you put a 1.5- percent ash product like CI-4+ into your engine, you may only get to 100,000 miles before you need a cleanout.

Lowering emissions – increasing issues
Aside from the exhaust aftertreatment devices, the 2007 engines have several other characteristics – primarily high soot levels and high heat – that require additional changes to the oil formulas.