Which statement is correct about draining fluid from a transmission pan?

Draining fluid from a transmission pan primarily involves facilitating the removal of the majority of the old transmission fluid. This process typically consists of unbolting the pan, allowing the fluid to flow out, and capturing it in a suitable container. Since the transmission fluid is thick and tends to cling to the sides of the pan and within the transmission, while the majority of the fluid is removed through this method, it is essential to note that it does not extract 100% of the fluid.

The idea that 'it removes most of the fluid' accurately reflects the common outcome of this procedure, making it the most suitable response. The process can clear out the majority of the used fluid, which helps in maintaining the efficiency and performance of the transmission.

Other options do not correctly represent the outcome of draining a transmission pan. One option suggests that all fluid must be drained, which is impractical and unnecessary with routine maintenance. Another option refers to only minor fluid changes being conducted in this manner, which does not reflect the broader applicability of draining for maintenance. Finally, the idea that only rusted fluid is removed misrepresents the purpose of the drain clean-out, as the focus is not solely on removing degraded fluid but rather on performing necessary maintenance for optimal functioning.