It's a Volvo seal, doesn't need to be a Volvo engine. If it's sat for 10 years, change it.
It is a Volvo Penta stern gland seal. They are very good and durable and should be perfectly OK through lack of use and in the dark. The VP stern gland must be burped every time you relaunch or after drying out. You just need to release any trapped air inside the seal to ensure the seawater comes into contact with the rubber bearing and seal inside the stern gland as the water lubricates it and keeps it cool. You either need to pinch the nose (forward part) of the black rubber with your fingers so distorting the rubber to upset the seal until water starts to leak out, or, as I find easier, just push the nose to one side which has the same effect. You also need to inject some VP stern gland grease into the seal. Buy a tube (about the size of a tube of toothpaste, which will last you for 10 years) and it’s a simple job using a plastic drinking straw. The little tube of VP grease has a nozzle that inserts in to a drinking straw. As you squeeze the tube of grease you can see the length of straw that gets filled with grease (you can calculate the length required for 1cc). Now flatten 20mm of the end of the tube so it is flat, slide that flat piece under the lips of the seal inside the nose, moving it around as you slide your fingers along the straw to squeeze the grease out until it is all gone.
