DF200APX - LU, why 3 holes?

[Bar_Stroll]

I just purchased twin df200apx's and I'm currently performing the 20 hour service. Why is there 3 drain/level/air plugs on the lower unit opposed to the standard 2? I've read the manual and it doesn't seem to make much sense to me.

I don't think it will make any practical difference, just wondering.

[Striperk9]

same on my DF200Z

I have the same on my 2005 DF200Z. I think the third hole allows you to fill from the top, and acts as a vent.

Nothing I have heard from anyone official. Just only explanation I could think of.....

If you have ever tried to add lower unit fluid to the vent, you probably know what a pain that is. A third hole allows you to do this from the top. Just needs to settle before you check level again.

[Harper]

As far as I know, all lower units have three holes, at least the four cylinder and larger motors. My '07 DF150 has three. The upper is marked "oil", the one two inches below that is marked "oil level." I'm not sure of the function of the upper, but assume that striperk9's assessment is correct....an alternate means to refill. I never even bother to loosen or remove the upper plug.

[Bar_Stroll]

All the same assumptions I made. Not that there could be anything groundbreaking going on by having another vent but thought someone might have a specific way they fill up that is different than every other outboard.