Most manufacturers have yet to extend change intervals, but oil seems to thrive in the new engines.

Almost two years after the introduction of 2010 engine technology, the anticipated oil change extensions are mostly missing. The only exception, ironically, is Navistar, the one engine maker that chose to use exhaust gas recirculation without selective catalytic reduction to kill nitrogen oxides (NOx). The manufacturer improved filtration on some engines to make extending changes from 25,000 to 40,000 miles practical.

Any drain extension beyond factory- recommended intervals should be made only when oil samples are analyzed and properly interpreted, and when there is little or no variation in the truck’s operation.

Still, engine makers may loosen up their conservative intervals eventually. In the meantime, oil samples have shown some subtle changes since 2010. Today’s oils are better at handling increased heat, and they show reduced soot, which may extend oil life.

The expectation for extended drains has to do with the nature of SCR. The additional weight and complexity of the SCR system were justified based on higher engine efficiency, as well as the higher NOx levels in the exhaust, which would burn soot and almost eliminate active regeneration of the diesel particulate filter. This meant better fuel economy. Given that SCR engines would need much less EGR, the hope was they’d provide truck operators with a bonanza of extended change intervals, and thereby big savings in oil and filter costs.

While that’s a way off, Mack, Volvo and Cummins say they’ve seen changes in TBN [total base number] levels and oxidation rates in oil samples since 2010. Cummins has noticed a reduction in soot levels.

The EGR line on this 2010 Cummins ISX (right) is smaller than before, and the Volvo D13 (left) also has a small EGR passage because, with SCR, significantly less exhaust needs to be recirculated. Having less EGR reduces many of the stresses on engine oil.

For Mack, already low levels of soot did not change between the 2007 and 2010 engine technology changes required to meet U.S. Environmental Protection Agency emissions mandates, says company Director of Powertrain Marketing David McKenna. Reducing the EGR flow rate and improving combustion quality, he notes, can account for this.

Volvo Powertrain Director Ed Saxman, echoing McKenna, notes the 2010 engines have “yielded a minimal increase in oil oxidation, but not to the extent that it would affect performance. Also, we found that the prolonged high temperatures in EPA ’10 engines have had no effect on oil performance and do not affect drain intervals. Overall, the oil analysis report looks very similar between ’07 and ’10 equipment.”