Many vehicles do not have a drain plug for the automatic transmission. This is due to the fact that they do not require fluid changes very often, and when you do change the fluid, you need to change the filter or clean the screen, whichever it has. Therefore, to drain transmission fluid from most cars, it is necessary to remove the transmission pan. This allows the fluid to drain and gains access to the filter/screen. Also, it prevents accidental draining of the transmission when the novice is attempting to do an oil change.
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Many vehicles do not have a drain plug for the automatic transmission. This is due to the fact that they do not require fluid changes very often, and when you do change the fluid, you need to change the filter or clean the screen, whichever it has. Therefore, to drain transmission fluid from most cars, it is necessary to remove the transmission pan. This allows the fluid to drain and gains access to the filter/screen. Also, it prevents accidental draining of the transmission when the novice is attempting to do an oil change.