• To winterize your boat's fuel system, follow these simple steps: fill up your fuel tanks, change your fuel/water separator, and add a fuel stabilizer like Techron Marine.

  • Then, run your engine(s) long enough to work the old fuel through, and get treated fuel into all the lines and through the engine(s).

  • If you're searching for more boat winterization tips, read How to Winterize a Boat, How to Winterize a Four Stroke Outboard and Shrink Wrapping a Boat.

The rules regarding how to winterize a boat have changed in recent years thanks to the proliferation of ethanol in marine fuel, and nowadays, winterizing your boat’s fuel tank is just as important as preparing the engine itself for a winter slumber. That’s one of the reasons why quality fuel additives like Techron Marine have become a must-have, come winter. Check out this short video, to see the basic—but important—steps to winterizing your fuel system and ensuring that when spring arrives, your boat will run smoothly.



Let’s boil all that down into a simple list:

  1. Fill up your fuel tanks. Large volumes of air in them will increase the possibility of condensation forming, and water tainting the system.

  2. Change your fuel/water separator. If you don’t have one, add it—these are your final line of defense against water in the fuel.

  3. Add fuel stabilizer like Techron, which is a new, scientifically-formulated additive designed specifically for marine use by Chevron.

  4. Run your engine(s) long enough to work the old fuel through, and get treated fuel into all the lines and through the engine(s).

There’s an added bonus to running Techron through your fuel system, too: it’s formulated to help remove deposits from the system, and fight corrosion at the same time as it stabilizes that fuel—which it can do for up to two years.

Fuel tanks are susceptible to water accumulation due to condensation if they’re left only partially full through the winter lay-up, so be sure to visit the fuel dock and fill up before you pull your boat out of the water. Photo Credit: Joe Mabel.

There are also a few additional steps many engine manufacturers agree are good for the boat, which may or may not be appropriate depending on the type of boat and power system you have:

  1. Be careful not to over-fill the fuel tank, and leave enough room for expansion when the weather warms up. But at the same time, do not cap any fuel tank vents. While you want to minimize the possibility of condensation, if the fuel tank can’t breathe expansion damage can occur.

  2. Shut off the fuel valve at your boat’s tank, if it has one.

  3. If you have an older carbureted engine, either shut off the fuel valve or remove the fuel line and run it until all the fuel has burned out of the system and the engine runs out of gas. On some engines, it’s just as easy to drain the carb’s float bowls.

Once the engine and the fuel systems are taken care of, of course, you’ll want to deal with all the other systems on your boat which need winterization. Then it’s time to decide how to cover your boat, or if shrink wrapping is the method you’d like to use.

Wait a sec—what if you live in a region where winterizing needs are borderline and you may be able to enjoy a few warm winter afternoons out on the water? With modern outboards (which drain completely when tilted down), you can skip the engine winterization steps like fogging and running the fuel out, and your boat will remain useable through the winter. Do so, however, and you need to make sure you hook up a water supply and run them until they’re thoroughly warmed up at least once every three weeks.

The plumbing and fuel systems are a different story. Naturally you can still run your boat without using the winterized the head and freshwater systems. And as far as the fuel system goes, just as long as you refill the tanks and add the corresponding amount of Techron Marine after the fill-up, your boat should keep on running great. In fact, the folks at Techron say that the best idea is to add this stuff as you fill up at all times of the year, to keep that fuel system clean and water-free. And considering the ethanol issues that so many boaters seem to constantly battle, we’ve got to agree.

Treating with Techron on every fill-up is a good move.

For more information, visit Techron Clean.

Editor's Note: This article was originally published in November 2010 and updated in October 2018. Promotional consideration for this article was paid by Techron Marine/Chevron Lubricants.

Written by: Lenny Rudow
With over two decades of experience in marine journalism, Lenny Rudow has contributed to publications including YachtWorld, boats.com, Boating Magazine, Marlin Magazine, Boating World, Saltwater Sportsman, Texas Fish & Game, and many others. Lenny is a graduate of the Westlawn School of Yacht Design, and he has won numerous BWI and OWAA writing awards.