Winterization Frequently Asked Questions

How do I winterize my MerCruiser product?

Because of variations in models, it is not possible to include this information for all of our products on this website. We recommend that you have this procedure completed by an authorized dealer. The raw water section of the cooling system must be COMPLETELY drained for winter storage, or immediately after cold weather use, if the possibility of freezing temperatures exists. You can refer to your owner's manual or service manual for the location of the drain plugs. Failure to do this may result in trapped water causing freeze and/or corrosion damage to the engine. Damage caused by freezing or improper winterization IS NOT covered by the MerCruiser limited warranty.

Do I need to put antifreeze back into the cooling system after draining?

It is not essential to fill the cooling system with antifreeze if you are absolutely sure that no water remains in the system. However, for added assurance we recommend that this be done. Damage caused by freezing or improper winterization is not covered by the limited factory warranty.

How many drain plugs are on my engine and where are they located?

For specific information you should consult your owner's manual, service manual, or check with your local authorized dealer. Complete dealer network can be found on our website.

Should my sterndrive be stored in the up or the down position?

If you store your sterndrive installed on your boat, you should keep it in the down position. Otherwise, the rubber bellows in the transom assembly can become permanently deformed and fail.

Do I still need to have winterization performed by my dealer if I have a self-drain system on my engine?

The drain system on your engine is NOT intended to replace full winterization. It is for extending your boating season by allowing the cooling system to be drained after use if there is a risk of light freezing weather and you will be boating the next day. For full extended winter storage, after completely draining the cooling system, Mercury MerCruiser recommends the use of propylene glycol antifreeze (with a rust inhibitor for marine engines) in the seawater section of the cooling system. The fuel system must have fuel stabilizer added and the system must be fogged with 2-cycle oil. We strongly recommend that your product is winterized by an authorized MerCruiser dealer. Damage caused by freezing or improper winterization is NOT covered by the limited factory warranty.

Can I use propylene glycol (RV antifreeze) in my engine?

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.