Run the engine — don't drip stabilizer into the carburetor

Adding stabilizer directly into the carburetor bowl is overkill if you’ve treated the tank and run the engine for a few minutes.

Stabilizer doesn’t need to touch the carburetor directly; it just needs to be in the gasoline. When you pour the correct dose into the tank and let the engine idle for a few minutes, the treated fuel works its way into the bowl and replaces whatever was sitting there. That’s the whole job done.

If you skip the running step and store it, then yes, you’ll have untreated gas in the bowl. But the fix for that is to just drain the bowl, not inject stabilizer through the mixture screw hole. That’s messy, easy to strip, and completely unnecessary when the fuel system is already protected.

The only time I’d consider direct injection is if you’re storing an engine with a carburetor so gummed up that you can’t get it running — but then you’re cleaning it, not stabilizing it.

Run it for five minutes before you put it away. Future you will thank you for not making a sticky screwdriver situation.