The transmission in your vehicle serves to transmit engine power from the engine to the wheels across a wide range of conditions and vehicle speeds. It does so through a system of gears and other moving parts inside. Most cars, trucks, and SUVs on the road today feature automatic transmissions that shift gears on their own when directed to do so by a computer. But some vehicles have manual transmissions, where the driver manually shifts between gears while driving.
In either case, automatic or manual, the components inside your transmission are lubricated and cooled with a special oil. A manual transmission fluid change is a service aimed at replacing the old fluid inside your manual transmission with fresh fluid.
Changing the fluid in a manual transmission is more like changing the oil in an engine than changing automatic transmission fluid. It is closer yet to changing the fluid in an axle differential or transfer case. The process is fairly straightforward. A technician removes a drain plug at the bottom of the transmission casing, collects the old lubricant for proper disposal or recycling, and adds fresh fluid with a pump.
While the service might be simple, it is worth noting that your vehicle needs to be safely lifted and supported in the air for access. The correct type and amount of manual transmission fluid is essential. And some manual transmissions require a special pressure pump to install the new fluid.