Question: I recently purchased a used sailboat equipped with a saildrive. Unfortunately none of the manuals came with the boat so I am learning as I go. One of the things I want to verify is exactly where I check the oil level for the saildrive unit. The assembly under the boat looks just like an outboard engine set-up but I can’t see the fill plug. The drain plug is quite obvious. The unit is a Volvo Penta and access to the engine is a bit difficult on this boat. Help!

The red handle is the dipstick.

The red handle is the oil dipstick on the Saildrive.

Answer: Unfortunately access to routine service points is something that some builders overlook when they install marine systems. On the Volvo Penta saildrive the gear case check and fill point is located inside the boat at the very top of the reverse gear assembly. This may be very hard to get to on your boat, but the red handle shown in the center of the photo is the oil dipstick for the transmission (reverse gear).
The Volvos are also equipped with a suction tube located next to the red check point. (Shown here in the lower center of photo.) This is to facilitate using a pump to draw the oil out of the gear unit for a full oil change with the boat in the water.
Volvo recommends synthetic oil for this application. The oil is available through your local Volvo Penta dealer. The good news here is that as long as the oil on the dipstick is not milky colored, which implies water contamination, you should not have to change it very often. Volvo recommends a change at what amounts to every two years or about 100 hours of use. Yanmar also recommends changing it every 100 hours. Many would argue that this is unnecessary if the oil is not discolored. I would tend to agree based on my own experience, but I can’t really suggest that you ignore manufacturer recommendations.