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Related Articles, Synthetic Diesel Oils

Industry Testing Confirms Synthetic Diesel Oils Reduce Emissions

New Environmental Protection Agency (EPA) pollution regulations, requiring a 50 percent reduction in diesel emissions, went into effect this past October. Recently, the EPA approved even stricter emission limits set to go into effect in 2007. After-treatment devices for exhaust  gases are generally regarded as the solution to meeting the new requirements, but high-performance diesel lubricants are also effective tools in fighting excessive  diesel emissions. In fact, recent independent tests confirm that PAO-based synthetic lubricants can dramatically reduce particulate emissions, while also improving fuel economy. 

Two tests conducted by independent laboratories in Europe compared different 5W-30 synthetic PAO based lubricants with a 15W-40 petroleum oil and a 5W- 30 VHVI (Group-III) based oil. The first test was conducted on a six-cylinder EURO II emission level engine with the following characteristics: direct injection diesel engine with turbocharging and intercooling; displacement  of 11.95 liters; maximum power of 260kW at 1,800 revolutions per minute; maximum torque of 1730 Newton meters (or U.S. lb. ft.) at 1,080 rpm and 213,967 miles covered at start. The engine ran on typical 2001 U.K. pump fuel, with 30 ppm sulfur, six percent mass polycyclic aromatics and a kinematic viscosity of 2.9 cSt at 40 degrees C. 

Testing followed the ECE R-49 13 mode cycle required for EURO III emission requirements, as well as the new European Transient Cycle (ETC) required for EURO IV. Rapid load changes take place during this cycle, representing particulate emissions on the road and usually revealing higher emission levels. Four cycles  were run at a test cell temperature of 5 degrees C. The European Transient Cycle ran three times, a cold-start cycle from 0 degrees C and two hot-start cycles. Testing concluded with a ECE R-49 13 mode cycle. After each oil was tested, it was drained and the next lubricant was introduced using a double flush. Results were compared against a 15W-40 mineral-oil baseline.

Results for the ECE R-49 13 cycle indicated that the PAO-based diesel oils significantly reduced emissions when compared with the other oils. When compared to the 15W-40 petroleum oil, the PAO-based oils reduced particulate mass by up to 32 percent, and when compared to the 5W-30 VHVI oil, they averaged a 13 percent reduction. 

Results for the European Transient Cycles were even more dramatic. Particulate mass was reduced between 30 and 55 percent when compared with the petroleum oil and up to 47 percent when compared with the VHVI oil. 

The PAO-based synthetic oils dramatically reduced the total number of particulates in the 36 nanometer to 7 micron size range when compared with the other tested oils. Particulates in this size range include small carcinogenic particles and large particles visible as black smoke. 

The low friction properties and high viscosity indices of synthetic PAO-based diesel oils allow them to be formulated with lower viscosities than conventional oils. This yielded a 2.4 percent reduction in fuel consumption for the PAO-based fluids in the test. This increase in fuel economy, coupled with extended drain intervals, can generate significant savings for fleet managers. 

The second test, conducted according to the U.S. FTP transient test procedure, was run on a six-cylinder EURO II emission level engine with the following characteristics: direct injection diesel engine with turbocharging and intercooling; displacement of 5.96 liters; maximum power of 177kW at 2600 rpm and maximum torque of 840 Nm. The fuel complied with CEC-73-A-93 requirements and had a 500 ppm sulfur content. 

The test compared the emission levels of 0W-40, 5W-40 and 5W-30 PAO-based synthetic lubricants with a 15W-40 petroleum reference oil and a 5W-40 VHVI lubricant. Test lubricants ran in the engine at 75 percent speed and load for 10 hours, and the engine was flushed between tests. 

When compared with the other oils, the synthetic PAO-based diesel oils reduced particulate emissions as much as five-percent from cold start, while improving fuel economy by as much as 1.2 percent, demonstrating that high-quality synthetic diesel oils can  play a big role in reducing exhaust emissions in heavy-duty diesel engines. 

AMSOIL Synthetic Diesel Oils incorporate PAO technology and top quality additive packages, dramatically reducing exhaust emissions and improving fuel economy, while providing the ultimate in wear protection for extended drain intervals.

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