question about fuel

@mimico (3618)
May 28, 2008 4:53am CST
I have the bad habit of filling up when my tank is half empty because I'm scared of running out of gas. Does this mean that my old gas remains stuck in the engine? Or does the old gas and new gas mix together? In relation to this, does anyone know if gas becomes old? And what's the difference between fresh gas and gas which has been sitting in my engine for some time (over a week?)? Thanks. :)
1 response
• United States
28 May 08
First off, old gas doesn't remain stuck in the engine. Your tank is one big tank, not a resevoir type deal. Now if you go refill your tank, even at 1/2 a tank that has been sitting there a month or even a year, the old gas will mix with the new gas and it will be fine. Gas does not become old, it does however, become more concentrated because what water there is mixed with the petrol will evaporate. And that is the difference between the new and old. Water content. It is why people in hotter climates have to fuel up more. The water level decreases the amount of gas with time.