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The Penn State Microoxidation Test has been adapted for use with mineral oil base stocks and fully formulated automotive crankcase oils. Tests under nitrogen and air atmospheres coupled with analyses using gel permeation chromatography (GPC) and clay column adsorption provide for a semiquantitative analysis of the products by elution time (apparent molecular size). This test procedure allows for primary and secondary oxidation reaction rate studies after substantial quantities of the lubricant have been oxidized. Time-temperature studies can show the effectiveness of base oil quality as well as effects contributed by additives. A general time-temperature equivalence in the range of 200 to 225°C has been demonstrated for a series of formulated engine oils. Microoxidation tests have been compared with III-C hot engine tests for a series of ASTM reference oils.

Sequential four-ball wear tests have been used to evaluate automotive crankcase oils for use as heavy-duty hydraulic fluids and automotive crankcase lubricants. This test technique has been adapted for use with steel-on-steel, steel-on-ceramic and ceramic-on-ceramic bearing systems. In addition to the conventional “run in” and “steady-state” wear studies, the data produced have been used to interpret bearing unit load levels for the various bearing systems involved. The data produced show that in many cases hybrid bearing systems (steel-on-ceramic) and ceramic-on-ceramic bearing systems may be useful at higher unit loadings than the conventional steel-on-steel systems. These studies focused on achieving low boundary lubricated wear rates. The bearing unit loadings were obtained from the unit bearing pressures after the “run in” of the specific bearing system.

The Penn State Microoxidation Tester coupled with gel permeation chromatography and clay column adsorption techniques has been demonstrated to be an effective tool to provide semi-quantitative analysis for automotive crankcase lubricant deterioration. This test simulates engine piston-cylinder zone high-temperature thin-film conditions. Oxidative behavior of a series of ASTM Sequence IIID hot engine test reference oils (with unknown base stocks and additive packages) has been found to be comparable to and consistent with that of a model fluid formulated with a good quality conventionally refined heavy neutral and a simple additive system composed of phenyl alpha naphthylamine and zinc dialkyldithiophosphate. Further simplification of the test procedure for evaluating varnish and deposit formation tendencies proves to be an effective aid in discriminating base oils as well as compounded fluids with a minimum of analytical equipment.