If you will be changing motor oil and outdrive oil, for the engine you can use a 15w/40 like Rotella, or a 25/40 like that sold by Merc or Quicksilver, the drive oil you should be using Volvo's I have heard of problems using other brands.
For the engine winterization, after changing the motor and drive oil (I always like to run it again to check for leaks, proper level) if you have a carburated engine (GL is a carb correct?) I would fog the engine through the carb to protect the cyls and valves from moisture over the winter.
After that, you have to be careful to drain everything where water is present, the V8 engine has 2 drain plugs on either side of the block forward of the starter on the starboard side and the oil filter mount on the port side, they can be tough to get at but you must drain them and poke the holes to make sure rust flakes are not clogging the drain. Next for the engine, you remove the bottom end of the big hose connecting the front water circulation pump to the thermostat housing, and let that drain. You can reconnect that hose and replace the drain plugs.
You will also drain the exhaust manifolds, via the drain plugs, they can be on the bottom edge or rear edge of the manifolds. Poke those holes too.
For your raw water intake system first mark the hoses on the impeller housing so you don't mix them up and disconnect them. For the one going up to the thermostat housing, just make sure it drains, then you can re-connect it. For the one that comes up from the transom mount, point it down in the bilge to drain it. For the next step make sure the outdrive is all the way down. Now hold up the hose and fill it with whatever marine antifreeze (if it gets really cold where you are, then use -100) till it runs out of the water intakes of the outdrive. This will push any residual water out of that hose & the P/S cooler on the back of the engine. Reconnect those hoses.
If you want to fill the now empty engine & exhaust with AF, here's how I do it. Disconnect the top end of that big hose that runs between the water circulating pump and the stat housing. Put a funnel in it and fill it till it spurts out of the 'stat housing. Now the engine is full, reconnect the hose.
You can fill the manifolds the same way via the hoses from the stat housing. When they are full you will hear AF running out on the ground. This method is safer than trying to suck in AF via the water muffs on the outdrive. Keep in mind you must use a non toxic antifreeze for this, no matter what you do some will get spilled on the ground. You're going to need about 5 gallons of AF for the V8 engine.
I remove the outdrive after doing all this to check the bellows, gimble bearing and u joints. Then reinstall it in the spring.
