i never really understood this logic, but i hear it all the time. if you consistently wait until you are empty to fill up, haven't you basically used all the good fuel, and minimize the amount of "crap" left in the car every time you fill up. if, on the other hand, you always leave like a 1/4 of a tank when you fill up, it seems like you will be MORE likely to have "crap" in your gas tank, as you are always leaving some amount of old gas in the tank. sure it mixes with the new gas, but it seems like this method is designed to maximize the crap that builds up, so that if you ever do run on empty you actually might be getting bad gas at the end.

similar theory to always getting gas at busy stations, so that you get "newer" gas which supposedly is better instead of filling up with old gas from stations that don't get replenished as often. don't you want as much new gas in your tank as possible, so theoretically try to consistently get down to empty to constantly put in fresh gas? like i said, i've heard this over the years from many different people, i've just never understood the logic...

 

If I had no choice but to go to a cheap gas station I try to run it down to empty then fill it back up with exxon or shell.

 

I think instead the theory is that over time, all gas will leave gunk (water, particles, etc. that drops to the bottom of the tank. If you never get to the "gunk" level, you don't suck in that gas, although that's also what fuel filters are for. I subscribe to this theory, but don't think it's a huge problem either way. Regarding mixing gas, that happens anyway, and unless you're storing your car it's unlikely to have time to get "old".

Agree on hitting busy gas stations, the old ones with the ancient fuel tanks may have all kinds of crap in them.