Don't know where you are but up here in the Great White North we usually put the raw water
intake hose in a bucket of 50/50 anti freeze, start the engine, and pump
the stuff through till it comes out the exhaust
. Make sure you put a bucket under the exhaust
to catch the stuff that comes out and properly dispose of it. If the engine is raw water
cooled, take the thermostat out first. Some people like to take the impeller out after running the anti freeze through, others leave it in. No need to drain anything. You should loosen the alternator
belt for the winter.