Development of a New Heavy-Duty Automatic Transmission Fluid C-4 Specification

Allison Transmission Division of General Motor Corporation has developed a new high performance heavy-duty automatic transmission specification. The new Allison C-4 specification has been designed to meet higher ATD customer expectations and replace the 12-year-old Type C-3. The new C-4 specification includes a higher temperature, more severe oxidation requirement and a new non-asbestos clutch friction test. It also incorporates a fluoroel-astomer seal compatibility test and more demanding anti-foam and anti-copper-corrosion requirements.