2010 Engine Performance

John Baxter | March 01, 2011

Oil change intervals getting longer

It’s too early to tell what the ultimate maintenance picture on selective catalytic reduction engines will be, but prospects for extending oil change intervals appear to be improving.

Schneider National’s Steve Duley says the fleet’s oil analysis results for the 2010 engines show a “slightly diminished soot production rate. In the environment we run, our engines don’t have a tremendous appetite for TBN and we don’t see a lot of oxidation forming even as we push out to very high drain mileages.” TBN (total base number) measures the ability of the oil to combat acid. If TBN remains high enough, the oil is still protecting the engine.

“Wear rates are still quite low, which is different from engines from the early ‘90s, but the 2010 drains we run are at or greater than the 2007 product,” Duley says.

Volvo’s Jim Fancher says oil degrades “at a slower rate with the new emissions system.” However, he adds, “With our 2007 engine, Volvo extended oil change intervals from 20,000 to 35,000 miles in a normal application. We maintained this 35,000 interval on our 2010 engines.”

Mack’s David McKenna says the introduction of ultra-low sulfur diesel fuel for 2007 “helped offset some of the impact of increased EGR flow rates. We are reviewing 2010 data to determine if drain intervals can be extended, with a decision expected around mid-year.”

McKenna cautions that oil analysis alone shows a limited picture of the difference between 2007 and 2010. “Soot accumulation is very low in both and the effects on viscosity should be similar, perhaps with a slight reduction in TBN depletion for 2010. No change whatsoever with coolant conditioning. But, fan on-time has been reduced as a direct result of less EGR. Additionally, we now have a heavy-duty multi-speed fan drive as standard equipment on the Mack Pinnacle. This has resulted in a considerable improvement in drive belt wear and tensioner life.”

Cummins’ Zack Ellison also notes that while the company has not modified its oil change interval recommendations yet, “analysis reports do show that TBN depletion rates are just a little lower. The factory Cummins Filtration filters were optimized for the 2007 engines by altering the flow rates through the full-flow and bypass filers slightly. With better engine tuning, there’s less unburned hydrocarbon in the oil in 2010 — a prime contributor to plugging in the past.”

Daimler Trucks’ Brad Williamson reports the company’s 2010 Detroit Diesel engines are “a benchmark with a 50,000-mile service interval. We will continue to press ahead on longer service intervals and reduction of environmental impact from used engine oil and filters.”

He says the company’s seen no particular concerns with maintenance stemming from the 2010 SCR technology, though customers’ use of counterfeit Detroit Diesel oil filters has “created several non-warrantable engine failures.”

Optimized 2010 timing rejects less heat, too, Ellison says. “There’s been no change in radiator capacity, but now there is more reserve. With the latest coolants, and mid-stop cylinder liners, cavitation is something we rarely hear about any more.”

Ellison also notes that Cummins’ interval for cleaning the doser inector has risen from 125,000 to 150,000 miles. “In many applications, there’s no [diesel particulate filter] regeneration, so soot clogging of the nozzle is less and less common.”