What color is optimal for newly added automatic transmission fluid?

Newly added automatic transmission fluid is typically characterized by a bright red color. This color serves both functional and diagnostic purposes. The red hue indicates the fluid's freshness and effectiveness in lubricating and protecting the transmission components. Over time, as the fluid ages and becomes contaminated with debris and friction materials from the transmission, it may start to darken, eventually turning a brown color. Thus, the optimal color for new automatic transmission fluid is a vibrant red, which helps mechanics and vehicle owners easily identify its condition during checks or maintenance.