What is the correct method to check the fluid level in a manual transmission?

The appropriate method to check the fluid level in a manual transmission is to remove the fill plug. This is because the fill plug allows access to the transmission's internal fluid level directly, making it possible to determine whether the transmission is adequately filled according to manufacturer specifications.

When the fill plug is removed, you can check the fluid level by feeling for fluid at the opening. The correct level should be at the bottom of the fill plug hole; if fluid can be felt at the hole, then the level is sufficient. If it is low, additional fluid can then be added through the same opening.

Other methods, such as using a dipstick or removing seals, are not directly applicable to manual transmissions, as they typically do not have a dipstick like automatic transmissions do. Removing the rear seal or shifter is also unnecessary and not a standard procedure for checking fluid levels, as these actions do not provide the needed access or information regarding the transmission fluid level.