I use 20% nitro fuel, it's the traxxas brand, I think it's top fuel, it hasn't really worked much since I had it but after the guys at the shop I got the car at messed with it it worked long enough to break the engine in 4 tanks worth of idling, 1/4 throttle, 1/2 throttle and 3/4 throttle I live at 9500 ft so the settings could be quite far off, I now know factory settings so I have started there and worked my way around trying to make it run better. when I adjust the carb needle it dosen't seem to really help almost at all, and it won't stay running for long at all, I don't know if it's just the altitude or if it's the cold of if it just dosen't work but I have had too much stress from it, and today I got dumped by my girl and that is making things even worse. if you think that I can make it work I will re-install the engine and carb and start tinkering with it but if you think it's a messed up carb I will just send it in to gs. my engine is the stock.21, glow plug is stock as well.tempature has ranged fromprobly 30-40*degrees. it did run for a while maybe 1/2 a day when I was breaking it in but when I was trying to do the full throttle breakin part it just kept dieing and now it's not working hardly at all, it will idle then die, no matter how much I try to adjust it.