Take your vehicle for a test drive. Manual transmissions differ from automatic transmissions in that they're much simpler and easier to maintain. These transmissions do not have filters or cooler ...
If it's beneath them, a top-up or flush could be in order; the same if the fluid is gritty or dark. To add extra transmission fluid, you can simply use a funnel while the dipstick is removed.
Some auto repair shops will ... insists that you need a “fluid flush” to keep your car running well—for example, many newer cars have a “lifetime” transmission fluid that shouldn ...