I observed following weired fact. Suppose I have 5 ltr. bad fuel with kerosene mixed. I put good fuel approx. half tank. Fuel gauge is showing absolutly half tank. Then due to good fuel I start to get better performance. But as the fuel gauge comes near reserve mark performance start to decrease. Is it due to less fuel in tank OR Density of kerosene is lighter than genuine diesel. So as the kerosene enters which is bottam of tank enters in engine & drop in fuel gauge drop in performance? Do I always keep fuel level more than half tank? OR Is it programming in ecu? I mean engine runs on lean mixture as per signal to ecu from fuel gauge? One more thing. I get differant performance at hot noon & differant performance in cool evening & night. Please explain.