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The API has established lubricant specifications, which include standard tests for ring and liner wear. The Mack T-10 is one such test, performed on a prototype engine with Exhaust Gas Recirculation (EGR). At EOT, the liner wear is measured by profilometry, while the ring wear is measured by weight loss. It was decided to monitor the wear of the rings and liners during a full-length T10 test in order to observe the evolution of the wears and wear rates over the course of the test, by using the Surface Layer Activation (SLA) and Bulk Activation (BA) techniques. Three different radioisotopes were created, one in the liners at the turnaround zone, one in the chromium-containing coating on the ring faces, and one in the iron bulk of the rings. This enabled us to observe the wear characteristics of these three components separately. In particular, we were able to separate the face and side ring wears, which cannot be done with simple weight-loss measurements.

More stringent emission legislation has been a driver for changes in the design of Heavy Duty Diesel engines since the 1980s. Optimization of the combustion processes has lead to significant reductions of exhaust emission levels over the years. However, in the year 2002, diesel engines in the USA will have to meet an even more stringent set of emission requirements. Expectations are that this will force most engine builders to incorporate Exhaust Gas Recirculation (EGR). Several studies of the impact of EGR on lubricant degradation have shown increased levels of contamination with soot particles and acidic components. Both of these could lead to changes in lubricant requirements. The industry is developing a new specification for diesel engine lubricants, PC-9, using test procedures incorporating engines with EGR.