GM SAE Research Paper Summary

The following is a summary of the Society of Automotive Engineers (SAE) Paper #881825:
Correlating Lube Oil Filtration Efficiencies with Engine Wear
By David R. Staley of General Motors Corp.

AC Spark Plug and Detroit Diesel Corp. performed a joint study of the relationship between the level of engine oil filtration and Engine wear rates, and found finer filtration significantly reduced the rate of Engine wear.

Diesel and gasoline engine wear rates were established by building both a diesel and a gasoline engine with fully inspected wear components, and then inspecting them after the test. In both engines, the upper and lower main bearings, oil rings and compression rings were inspected. In the diesel engine, the cam lobe profile and cylinders were also inspected, while the piston pin bushings, piston pins and cylinder liners of the gasoline engine were inspected.

Contaminants were added for test purposes

The total test duration was eight hours. To accelerate wear, 50 grams of AC Fine Test Dust was added, in slurry form, to the crank case every hour.

Diesel engine wear tests were performed using filters with high efficiency ratings for particle sizes: 40-micron, 8.5-micron and 7-micron.

Gasoline engine wear tests were performed using filters with high efficiency ratings for particle sizes of the following sizes: 40-micron, 30-micron and 15-micron.

Analysis

The researchers found clearances in the diesel and gasoline engines varied between 2 and 22-micron during engine operations. That means particles in the 2 to 22-micron size range are most likely to damage engine parts. Particles smaller than 2-micron will slip through the clearances without damaging bearing surfaces.

Conclusions

The researchers drew the following conclusions:

Abrasive engine wear can be substantially reduced with an increase in single pass efficiency. Compared to a 40-micron filter, gasoline engine wear was reduced by 50 percent with 30-micron filtration. Likewise, wear was reduced by 70 percent with 15-micron filtration. Controlling the abrasive contaminants in the range of 2 to 22-micron in the lube oil is necessary for controlling engine wear.

The Micron Rating of a filter, as established in a single pass efficiency type test, does an excellent job of indicating the filter's ability to remove abrasive particles in the engine lube oil system.

The smallest particles most popular filters capture with high efficiency are sized 25 to 40-micron, depending on the filter brand.