Field Trials for Engine Oil Specs?


Modern lubricant performance specifications usually contain a number of bench and engine tests, but an official with a German firm suggested recently that industry should also consider field trials as a way of verifying product quality.

Speaking last month at the Mineral Oil Technology Congress held in Stuttgart, Germany, by UNITI, the German association of small and medium-sized mineral oil companies, Intertek’s Simon Kraneburg contended that field trials can provide an economical way to gauge real-world performance.

Automotive engine oil specifications – whether developed by industry organizations or individual original equipment manufacturers – normally measure product quality through a combinations of engine tests or bench tests. The latter are performed in laboratories using actual vehicles or their engines mounted on stationary stands, while the latter are conducted on smaller, simpler apparatuses that often sit on a laboratory table.

Lubricant formulators have long used field trials, but most often during product development.

Kraneburg, who is senior business development manager for Intertek subsidiary KJ Tech Services GmbH, said it may sometimes be a better approach to use field trials in which numerous vehicles filled with the subject oil are operated for a prescribed period of time before performance is checked – sometimes by breaking down an engine to measure impacts such oil deposits or wear on a particular part, other times by testing oil samples. It is also possible to monitor the characteristics of the lubricant while in use on an ongoing basis.

For results to be meaningful, Kraneburg said, several aspects of the trial must be defined. A prescribed number of one type of vehicle should be used, he said, for uniform time and distance and under uniform loads, road conditions and fuel type. Oil drain and sampling intervals also need to be defined, as well as particulars of any testing or measurements to be conducted on lube or equipment.

Kraneburg said the benefits of fleet trials vary depending on the type of trial. Internal fleet trials can be more precise since operating conditions can be strictly controlled. Often they can be completed in shorter periods of time. They are more expensive than external trials, though, because of the cost of owning the vehicles and the fact that they are not being used in revenue-producing ways.

External trials cost less, but also introduce more variability since travel routes may vary and because of other factors such as weather.

Although field trials generally have greater variability than bench tests or engine tests in a laboratory, Kraneburg contended that they may provide more accurate information about an engine oil’s performance in the real world. Lab-based tests are often conducted under conditions that accelerate the impacts of factors such as heat or time so that test duration may be shortened.

Fleet testing with “specimen” vehicles occurs in an artificial and controlled testing environment, offers a choice of sample size and type and has an extended choice of measurements.  The strongest pros for this type of testing include its flexibility and the control over test environment and influences. Its shorter timeline is a plus, he noted. A con to this type is its cost, he said.

Kraneburg suggested that specification developers consider what they are attempting to accomplish before deciding whether to employ field trial tests. Making the right choice requires figuring out what to expect from a test under real road conditions. Developers should also consider factors such as timeline, budget, objective, availability for support, need for milestones and the ability to adapt from feedback.