When Ring Free first come out, I called Chevron Technical Support and asked them about the product. I got to speak with a guy on the development team who told me that in was a concentrated form of Techron. When used at the maintenance level (1 oz per 10 gallons), it brings the Techron level up to that present in Chevron (and now Texaco) gasoline. The idea is to protect the engine from deposits that form when "lower quality" gasoline is used. What that means is that if we are already running a high quality fuel, Ring Free is probably a waste of money. I use it now because I have no idea about the quality of the Rec 90 sold at my marina.
There are several BS posts that claim that Ring Free has changed its formula and now simply a solvent rather than a polyetheramine derivative (i.e. Techron). I have to call that BS because even without gas chromatography, my nose can pick up the same distinctive amine odor from the current product. The "plus" component found in the later versions of Yamaha fuel additives is to protect aluminum fuel system parts from ethanol related corrosion problems.
