lower unit oil capacity

[fluidjuice]

i have a 1991 40hp 4 cylinder merc ive just drained down and refilled lower unit oil, in my manuel it states that the oil capacity is 370ml , i could only get about 270ml in max.
i removed both plugs to drain, and filled from the lower plug untill oil came out of the top plug,replaced lower plug then top ,have i done this right if so why cant i meet the the oil capacity spec of 370ml, thanks

 

[electricjohn]

Re: lower unit oil capacity

Is there another smaller vent screw next to, but in front of, the larger one. My lower (90HP) has 2 vent screws due to a split reservoir.

 

[fluidjuice]

Re: lower unit oil capacity

No just one drain and one vent