Automatic Transmission Fluid Viscosity at Low Temperature and its effect on transmission performance

A LOW-TEMPERATURE study of the relationship between the performance of a step-type automatic transmission and the transmission fluid viscosity is reported in this paper.

It is shown that the low-temperature malfunction of these units is due to the viscometric properties of the fluid and that at the temperature at which the fluid reaches a certain critical viscosity the transmission will fail. A mathematical analysis of the mechanism of failure supports the conclusions drawn from the experimental study.*