40 hp 2 stroke 4 cyl. Mercury gearcase oil fill

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Re: 40 hp 2 stroke 4 cyl. Mercury gearcase oil fill

Hi there welcome to iboats! The drain plug on the bottom of the lower unit gear housing case is both the drain and fill screw. There should also be a vent screw a little higher up on the lower gear housing possibly on the port side of the gear housing.

You fill from the bottom up to the vent screw with the outboard in the vertical position making sure there are no air bubbles visible.

Hope this helps, good luck.:)
 
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