Changing lower unit oil? :confused:

[redneckboater]

I just recently aquired an 1971 20hp mercury outboard and I want to change the lower unit oil. I see there is a drain plug and a fill hole but there is no vent hole. Im afraid that once i drain the oil i wont be able to fill it because it will get air locked?

What should I do?
Thanks

 

[saumon]

Re: Changing lower unit oil?

Drain and fill holes are the same: the bottom one! Vent hole is up.

 

[Laddies]

Re: Changing lower unit oil?

The vent screw is a smaller srew on the same side that the drain is on above the cavitation plate and goes in at a angle