Fuel system additives, Good or bad? Options

[senick]

So I've heard some negative things about fuel additives for cleaning the fuel system, and I'd like some conversation on the subject. I've been using Gumout fuel system cleaner about every oil change thinking that it was an altogether innocuous compound. But I've read comments on here how similar products can damage the emissions components. I've recently had to change my 02 sensor, and I'm thinking that might be related to my use of gumout.
Are there any good products will no negative side effects? Is there even reason in the first place to use these?

[Galcobar]

That's surprising, you're the first person I've heard report that Seafoam through the vacuum system gummed anything up. I've used it myself in fact, to real effect. Seafoam actually works as a carb/throttle body cleaner.

Of course, one of those effects was to dissolve the carbon deposit which kept my slow leak on my oil pump seal to a drip, allowing it to become a fast leak, but that's not a negative for the product so much as it was an indicator I really needed to get that seal replaced.

This post has been edited by Galcobar: Aug 9, 2011 - 7:29 PM