Fuel Additives

The Nissan Maxima manual warns not to add fuel additives such as Gumout, STP Gas Treatment, etc. Suipposedly because they can contain solvents that cause harm, etc. What's your opinion?

Every time I change my oil I add either fuel injector cleaner, octane boost, etc. My 96 now runs better than it did two years ago when I bought it. I would just say, don't overdo it