any reason to put antifreeze in it? ----- YES
That should be it, right? ------- NO
So I will open this one single handle deal and take out the 5 drain plugs. If I take the 2 front hoses off one on each side and pour some RV antifreeze I should be good to go? ------- NO
suggest you read the owners manual for your engine. if you can't find yours, I posted a link that you can download one for free. One of the things that you will find in it is about that blue drain plug on the thermostat housing. ------ Surprise ------ the only time you should pull this plug is when you use the single point drain system while the boat is still in the water!
Can you "get by" following some of the advise posted above? Maybe, I did some pretty funky things the day I had to "make safe" 30 engines one October day in Minnesota. Missed a power steering cooler, but saved everything else.
a note on "pink" RV anti-freeze, it usually doesn't have enough corrosion inhibitors in it because it's for RV water systems. I highly recommend you spend a few $ more and get the right stuff. You have a single point drain system and it is very hard to properly winterize this system. This system has gotten a "bad" name because soo many people don't winterize it right. This leads to rust in the system and a cracked block a few years later. If you read the owners manual you might notice a lot of detailed instructions, but you won't find anything about how to fill the system with the correct anti-freeze. I asked MerCruiser why that's not covered? Was told that's because it's common sense. "we provide a pump on the engine to suck it up and so fill it just like you flush the engine with water" when I pointed out that some engines have trouble sucking it up. "well then you should use a pump to get enough pressure".
IMPORTANT: Mercury MerCruiser
requires that propylene glycol antifreeze, mixed to the manufacturers instructions, be used in the seawater section of the cooling system for freezing temperatures or extended storage. Make sure that the propylene glycol antifreeze contains a rust inhibitor and is recommended for use in marine engines. Be certain to follow the propylene glycol manufacturer's recommendations.
Manufacturers of outboard motors and MerCruiser inboard engines, with over 4000 dealers in the United States.
www.mercurymarine.com
QUESTION:
Can I use propylene glycol (RV antifreeze) in my engine?
ANSWER:
Propylene glycol antifreeze with a rust inhibitor is approved for use in the raw water cooling system for cold weather storage purposes ONLY. However, if your engine is equipped with a closed cooling system, you should always use a 50/50 mixture of ethylene glycol antifreeze and water in this system. Even if you don't live in a freezing climate, you should still use an antifreeze/water mixture rather than plain water. Antifreeze mixtures have superior anti-corrosion and boil over protection properties.
EDIT - your engine isn't registered with Mercury so you haven't been notified of any recalls or updates. Suggest you talk to your local dealer and get this registered in your name.