Why Do I Need a Transmission Service?

One of the most critical, unobtrusive and, therefore, often neglected parts of a vehicle is the transmission. While it isn't as maintenance-intensive as the brake system, for example, both manual and automatic transmissions require at least periodic inspections if not regular service to prolong their life. But before we explain how to best service transmissions, a brief explanation of how one works is required.

The transmission multiplies torque from the engine through a gear reduction and/or torque conversion. A typical manual transmission has anywhere from four to six speeds with the final or highest gear being either a direct 1:1 drive ratio or an "overdrive" ratio, less than 1:1. For the most part, they are trouble-free (except for the clutch, which can be problematic if adjusted incorrectly or abused). An automatic transmission, on the other hand, multiplies engine torque as it passes through the fluid coupling known as the "torque converter" and then through three or more separate gear ratios. The transmission oil is critical for lubricating the transmission and reducing friction. When the fluid breaks down and loses its viscosity, it no longer effectively lubricates the transmission. This causes premature and excessive wear and results in transmission failure.