TruFuel doesn't replace fogging oil.

Pre-mixed fuel like TruFuel protects your fuel system, but it doesn’t coat the cylinder walls, so you still need fogging oil for proper storage.

TruFuel is nice because it’s ethanol-free and stabilized, which means it won’t gum up your carburetor or turn into varnish over the winter. But that’s all it does. It sits in the tank and the carburetor. It never gets to the parts that actually rust — the piston rings and cylinder walls.

Fogging oil is sprayed directly into the spark plug hole. It leaves a sticky, oily film on the metal surfaces that prevents moisture from causing rust during months of sitting. Even in a 2-stroke, where the fuel already contains oil, that oil is thin and drains off. It’s not enough to protect against corrosion for months.

For a few weeks of storage, you can get away with just TruFuel and a full tank. For winter or anything longer, take the five minutes to fog it. Spray it in, rotate the engine a few times, and you’re done.

Future you, dragging the mower out in April with a clean carb and a free-turning engine, will be glad you did.