Hey bczoom - That Chevron site is excellent! </P>
We have a couple of old Ford, Ferguson, and Farmall tractors for mowing and we always use the lead substitute additives. It sounds like itis a good thing that we do. </P>
The best retail gas preservative (IMHO) is Fuel Fresh which is available at Briggs dealers. You can get a 1 oz. "pillow" or a quart. A lot of Corvette, aviation, and high performance people use it. It works in diesel as well since thecarrier is a refined light mineral oil. It is not water soluble so it won't help if there's a lot of water in the tank. </P>
I use it in over20 engines ( a nightmare) and never had a moments problem starting them after storage. (Except for pack rat damage...a whole 'nother issue.) </P>
There was some report along the lines that StaBil does very poorly in some of the ASTM tests for corrosion, oxidation, etc. Obviously they are aggresive marketers since they're on the big box store shelves - not nescessarily a ringing endorsement for quality. </P>
The best thing is to try some differrent types and see how they work for you. </P>