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New technologies are being commercialized across the automotive industry to address demands for improved fuel economy, emissions reductions, and improved customer satisfaction. Push-belt continuously variable transmissions (b-CVTs) are beginning to command a significant percentage of the market now dominated by manual and conventional automatic transmissions. In addition, automobile manufacturers plan to introduce the first traction drive toroidal-CVTs to the market place within the next five years. A review of the relative benefits and limitations of each of these automatic transmissions exists in the literature. In this paper we consider how the performance requirements of each of these automatic transmission systems impact automatic transmission fluid technology. The physical characteristics and screen test performance of two commercial ATFs, a b-CVTF, and two traction fluids were examined.

The Sequence IIIG is a newly developed 100 hour test used to evaluate the performance of crankcase engine oils in the areas of high temperature viscosity increase, wear, deposits, pumpability, and ring sticking for the North American GF-4 standard. Data from the ASTM Precision Matrix, completed in the spring of 2003, along with early reference data from the Lubricant Test Monitoring System (LTMS) showed unexpected test results for selected oils and indicated that percent viscosity increase and pumpability were highly correlated with oil consumption. This correlation led to an intensive study of the factors that influence oil consumption and an attempt to compensate for non-oil related oil consumption through a model based adjustment of the results. The study and scrutiny of the IIIG data has led to more uniform oil consumption in the test and improved test precision, and has eliminated the need for a correction equation based on non-oil related oil consumption.