OMC jet drive oil. How do I know its full?

[Huntleybill]

I just got my 1995 Four Winns and before I go out, I wanted to check some things over. There is a yellow screw on cap under the power head in the front of the pump ( I think that is the pump) I removed the yellow cap and I can see there is some oil in there but I don't know if it is enough or if not, what kind of oil goes in there? The level looks to be about 1" - 1 1/4" below the top.

Can anyone tell me if it is full, how full it needs to be, what kind of oil goes in there? My service manual hasn't gotten here yet and I'd like to use the boat.

Thank you