In July, we discussed the science behind engine oil development and testing. This included the steps required to create a fuel-efficient heavy-duty engine oil and the need to conduct field trials. This month, we’ll cover how a field trial can evaluate the fuel economy in trucks with different duty cycles in order to get a true picture of how they will perform. For example, Shell Lubricants uses field trials to assess how different viscosity oils impact fuel economy in different engine models in realistic real-world settings and to evaluate the efficiency of low-viscosity engine oil technologies. The overview below shows how the fuel economy effect of a lubricant can be accurately measured under real-world test conditions.
• Real-world urban and highway driving conditions: The type of driving for a truck plays a significant role in fuel economy, and trucks with different duty cycles, such as urban start–stop or high-speed, long-distance highway driving, will have different efficiencies. The Society of Automotive Engineers has developed industry-standard drive cycles designed to reflect this: SAE J1321 and SAE J1526. Shell uses these standards as a basis on which to design its field trials.
• Statistics driving precision: A single measurement does not give a result that you can trust. In field trials, Shell Lubricants recommends that measurements are repeated and averaged, and the experiments are carefully designed to minimize the variables that cannot be controlled such as weather and humidity. Each truck and lubricant are tested on all days of testing.
• Standardized conditions at trusted independent test houses: For fuel economy measurements, it is important to isolate the impact of the lubricant itself. These experiments are run at certified independent test houses that regularly conduct closed-track experiments representative of real-world driving conditions. Scientists work to design experiments to standardize what each truck and lubricant combination experiences by controlling those variables that can be controlled, such as load, driver intervals and oil flush procedures.
• Comparing the right oils: Establishing the proper parameters at the start of a field trial will provide the most meaningful results at the end. Tests can include oils currently on the market and will often include different development or prototype oils for evaluating their future use. There is typically a reference oil such as a CK-4 SAE 15W-40 oil and test formulation oils can go as low as SAE 0W-20.
For fuel economy measurements, it is important to isolate the impact of the lubricant itself. These experiments are run at certified independent test houses that conduct closed-track experiments representative of real-world driving conditions.
• Measuring fuel economy: Fuel consumption can be measured in a variety of ways. In Shell Lubricants fuel-economy field trials, fuel consumption is measured by weighing the fuel tanks before and after each test run and using electronic data loggers from the vehicle control unit. The fuel economy benefit is calculated relative to a reference lubricant.
• A wide range of engine manufacturers: Testing is done with engines from several manufacturers and types of technology so that the results are representative of what customers experience in the market. This has included up to six vehicles from different manufacturers, which are matched according to mileage and condition.
Field trials have shown that lubricant selection has a significant impact on fuel economy in real-world driving conditions. They are also an important element in the worldwide need to improve the efficiency of heavy-duty engine technology.
Dan Arcy is the global OEM technical manager for Shell Lubricants.
