I run Losi Nitrotane and for about a gallon.From day one I had problems with my .12 OS TZ leaning out at about half tank or less? I changed everything on my car from plugs,tubing,fuel filter...Then one day a guy at my lhs said they stop selling nitrotane 20% because people were having tuning problems with their .12's... He said it worked fine for .21's....Kinda weird I thought.. Then I put some Byrons in my truck and it ran flawless......Always wondered if someone had the same problem???