Modern Heavy Duty Diesel Engine Oils with Lower TBN Showing Excellent Performance

Over the last decades, heavy duty diesel engines have experienced many changes in design and operation. More stringent emission legislation has been a driver for changes in the design of heavy duty diesel engines since the 1980s. Optimization of the combustion process and the introduction of exhaust gas recirculation allowed for significant reductions of exhaust emission levels over the years, but the thermal loading of the engine and its lubricant has increased. In the coming years, diesel engines will have to meet even more stringent requirements for particulate matter and nitrogen oxide emissions. These low emission diesel engines are expected to be equipped with exhaust gas after-treatment systems. And, because some of the anticipated systems have shown improved durability with the use of low sulfur diesel fuel, it was mandated that, starting in late 2006, the sulfur in diesel fuel for on-highway use had to be lowered to a maximum of 15 mg/kg, thus enabling the use of these new emission control systems. At the same time, chemical limitations for sulfur, phosphorus, and sulfated ash were introduced for diesel engine lubricants. These changes in the chemical limitations for fuels and lubricants, and in engine design and operation, impact the formulation of future diesel engine oils.