When it comes to prepping outdoor equipment for winter storage, even an optimist knows that a gas tank that’s half full is bad news.

That’s because today’s gasoline is made with a percentage of ethanol, which can increase the chances of moisture buildup, corrosion and even phase separation in your engine, according to a news release.

That can lead to expensive repairs.

Fortunately, there are steps you can take to avoid these and other problems when it’s time to start your engines once again, the release stated.

Don’t drain the tank

Small-engine experts say that when you leave the fuel level low, it allows water vapor to condense on the walls of your fuel tank. It then runs down the walls and collects in the fuel. This is what causes phase separation.

When you start your engine in the spring, this water may run through your fuel system and can cause engine damage or even complete engine failure.

Water in a fuel tank also encourages corrosion. Particularly in today’s ethanol-blended fuels, when water and ethanol mix, it can become acidic and very corrosive.

Part of the problem is that when you think your engine is dry, there is still gas in your fuel system in small amounts. These tiny fuel droplets are surrounded by oxygen that can attack unprotected fuel and cause gum and varnish buildup.

Even the smallest amounts of either gum or varnish can cause a lot of damage inside a fuel system. For example, gum can settle on a seal surface, causing a leak or preventing fuel from flowing into the engine.

A dry fuel system also can damage seals and gaskets, according to the release.

They’re designed to be continuously soaked in fuel and play an important role in keeping fuel flowing to the right places in your engine and out of the wrong places.

When they are exposed to air for long periods, they can dry out and crack.

That can cause leaks and lead to costly repairs, the release stated.

A full tank, stable fuel

That’s why it’s important to stabilize your fuel and practice proper fuel management techniques with any equipment with a gasoline engine.

It turns out that filling your gas tank 95-percent full of fresh fuel and adding the proper dosage of a fuel additive can do a lot to protect a fuel system and engine by preventing fresh fuel from degrading, leaving deposits and corroding the system, according to the release.