Re: fogging Volvo Penta 5.7GXi
I'm leaving the winterization to the dealer. They do run it on muffs. If the block comes back cracked it's there nut and since the boat is still under warranty I have somebody to point to.
I believe there is a Volvo service bulletin around somewhere about the fogging of the engine. It is very similar to the Merc noted above
It is very easy to drain the block and manifolds though - there are 4 blue plugs total, 2 below the manifolds and 2 lower at the bottom of the block. They simply unscrew and fill your bilge with water

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You do also need to drain the impeller feed hoses and the big water hose from the thermostat and another to the fuel pump area.
I think if you want to do it yourself the safest way is to drain as described above and then pop the thermostat housing and pour antifreeze directly into the block. Do the same for all the hoses you disconnected, reconnect and sleep soundly for many months.
Cheers.