There’s a lot you can learn about the condition of your transmission just by examining the fluid. New transmission fluid is usually transparent, and relatively odorless. A few years ago, virtually every transmission fluid was red; technicians would aptly describe a transmission with exceptionally clean fluid as being “cherry.”
Today, many manufacturers have begun to stray from the traditional red color. Transmission fluids may be green, yellow, some may even have a bluish tint. But in virtually every case, clean fluid will look clean and smell clean. So checking the fluid’s color and giving it a little sniff is a great indication of whether your transmission is in good shape, or in need of service.