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I have seen a number of lubricant manufacturers refer to the 4-ball wear scar test as an indicator of how well the oil will protect an engine. Other larger companies tend to brush off the results of this test indicating that it isn't representative of actual engine conditions adding that because it is cheap to run, the results aren't worth much. What are your thoughts on this?"
The 4-ball test (ASTM D4172) is often used as a screening test for many different lubricant types that contain antiwear additives or similar base oil properties. Other tribo-mechanical bench tests are often used as well, including the Timken Test (ASTM D2782) and the Pin and V-Block (ASTM D2670). Because engines have different contact geometry, loads, metallurgy and speeds, numerous bench tests and test protocols are needed. It is not uncommon for several oils to be tested using two such methods and to find that the performance rankings between the oils to reverse (no correlation). This is why, among other reasons, Passenger Car Motor Oils and Heavy Duty Oils (diesel crankcase) are tested in actual engines using controlled methods such as ASTM D5533 Sequence IIIE and D5302 Sequence VE.
Jim Fitch, Noria Corporation
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