Fuel/Oil Additives again

I submitted this subject matter at a previous thread but missed the replies. I though there were means to go back to previous issues. Nonethless, businesses are making money manufacturing and selling fuel and oil additives. what's your take on this especially things like Slick, etc. Manyh chemical expert reports I viewed on several websites generally indicates that most are a waste of money and that most have been sued by the FTC. Most settled their respective suits except one. As they say if it's too good to be true, it is.