Oxidative properties of lubricants using thermal analysis

The development of automotive lubricants requires optimization of a number of performance parameters of both base fluids and additive systems. The final test of a lubricant requires that it perform well in a particular application or system. Prior to the final selection of a lubricant, a number of combinations of base fluids and additives need to be evaluated. The most practical way to do this is through inexpensive bench testing. The use of pressurized differential scanning calorimeter (PDSC), thermal gravimetric analysis (TGA) and thin-film oxidation tests will be described in the evaluation of several lubricants. Examples of some practical applications of the thermal methods to the evaluation of alternative fuels and lubricants, and to studies involving extended drain lubricants are reported. Incompatibility of alternative fuels and lubricants can result in significant extraction of some additives. Thermal analysis shows significant variation in stability of the fractions obtained from simulated crankcase tests. Results from some of the methods are compared. (C) 2000 Published by Elsevier Science B.V.