We did this a while back in this thread, without deciding much of anything definite.
I keep hearing from time to time that acetone makes a sensible gas additive, but there are reservations about its effect on gaskets. Googling produces the usual mix of opinions. I was wondering if anyone has additional info.
There are only two good products I can think of as fuel additives for a gasoline passenger car or light truck.
The first would be Chevron Techron. Won’t help your gas mileage unless it helps clean up the engine or injectors, but it’s a reputable product.
The second is the LubeControl company’s FP60 product. It’s along the lines of Chevron Techron, except the manufacturer reccomends using small doses with every fill-up.
There’s a rumor from a man I trust that the FP3000 product from LubeControl, which has completed SWRI testing but isn’t publicly available except to a select group, has shown 3% MPG improvements in diesel applications and 6% improvements in gasoline applications.
The downside is, last I checked the stuff will be expensive enough that the break-even point for using it occurs around $2.50 per gallon.