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Understanding lubrication failures at the shoe/swashplate contact of automotive swashplate compressors will greatly enhance the reliability of the air conditioning system. Maintaining proper lubrication is not always possible during transient conditions. Therefore, a method for detection of lubricant loss is of great interest to the automotive industry. Three methods for detecting lubrication loss were examined: contact resistance, acoustic emission, and dynamic pressure oscillations. A mobile air conditioning test stand capable of recording many system parameters was used. Oil return to the compressor was monitored using an oil separator and a refrigerant/oil concentration sensor. Data were taken during steady oil return rates and after oil shut off. The electrical contact resistance between the shoe and swashplate was used to indicate changes in the lubrication conditions at this critical interface. Measurements were taken at two oil return rates during steady oil return tests.

Since diesel engine oils are part of the low-emission equation, there has been stepped increases in the quality of crankcase oils with the stepped reduction in diesel exhaust emissions. The new API CG-4 oil category, was developed to address the Engine Manufacturers Association's (EMA's) needs for 1994 emission-controlled diesel engines. It also improves the quality of crankcase oils by using modern four-cycle diesel engine tests which: operate on low-sulfur diesel fuel, as used by all on-highway trucks in the U.S., have statistically defined test limits, are incorporated into the Chemical Manufacturers Association's (CMA's) rigorous code for qualification testing.