What is the best gas additive for cleaning fuel injectors and the inside of the engine?

Most vehicles need none. For routine fuel injector cleaning once a year, I use Techron. Can’t verify if it has done a good job or not.

Best way to keep your engine clean is to change oil every 5K miles or so.

Are you experiencing some particular symptoms that you need to deal with?

I agree. Once a year, I use a bottle of Techron or a can of Seafoam. They are both excellent products.

Me, too. Once or twice a year I put a bottle of Techron in the tank. And I doubt it’s really necessary.

Gasoline has plenty of detergent in it. Most cars never require any additional fuel system cleaning, regardless of what the magazine ads tell you.

I agree that gas additives are not needed and serve no purpose in today’s scenerio.

However if it helps you feel better a bottle now and then does no harm. Consider it like an occasional beer, does no real good but helps you sleep better for a buck or two.