I use the proper amount of MMO and StaBil at the same time for my carburated engines...lawn/snow equipment and 1980 V8 4bbl. Meaning, 4oz of MMO and 4oz Stabi(8oz) per 10 gal gas.
In my Firebird FORMULA V8-4bbl, I use a total of 16oz per the 20 gal tank of gas(8oz MMO/8oz StaBil). Engine runs smoother than ever before. Starts great, ildes smooth, excellerates well.
In my small equipment, I only have a small 2.5 gallon plastic gas can. Therefore, I use 1oz MMO and 1oz StaBil at the same time as the directions both say to use 1 oz per each 2.5 gallons of gas/4 oz per 10 gallons of gas. B&S, Tecumseh, and Honda small engines all run smooth and consistant all of the time. I can't beleive what a difference it has made. I don't know what got me doing this!
I have run, but no longer do...MMO w/Regane or Techron(or, one or the other by themselves) in my '04 Altima 2.5s without issue but, my wifes '01 Lexus RX-300 3.0L doesn't like it. It's the MMO that triggers CEL "all the time" with the Orig Equip AF/02 sensors as well as the replaced sensors. Her Lexus just doesn't like MMO in the gas tank. Fuel system cleaners are OK but "NOT" MMO, even by itself. So, I leave it alone until I think it's running a bit sluggish and then use some Regane or Techron by themselves...No CEL!