AcidHell2 said:
No, it's fine.
Most fuel tanks have the fuel inlet slightly above the bottom of the tank. Thus negating the crud problem.
the man makes a valid point. a lot of cars do have a slightly raised fuel intake. On medium-old diesels, or old petrol cars though, enough sludge can accumulate to mean that if you do run dry you'll take in a lot of sludge though. It usually just blocks the fuel filter on modern cars, but if the fuel filter isn't working right, it can cause a lot worse problems than that - fuel pump & injector type problems - big money and lots of downtime.
Also, you can get small amounts of water in the tank when you fill up - this is more an issue with diesels - which can build up over time.
It's not usually a good idea to run it till it's on fumes a lot, even if only because you might get caught with no fuel. If it's a diesel, running right to the bottom is NOT recommended - filters, and water drain plugs on filters are there for a good reason but they can only cope with so much abuse.
You do have the issue though, if you are always going round with >50% capacity, that you are using fuel to carry fuel.
My advice would be to not fill the car above 70% unless you absolutely need to, say, long journeys etc and not let it get below, say, 10% of tank capacity unless caught short - i've never had problems with fuel filters or anything to do with sludge (other than a couple of tanks i've had to flush) in 8 years of driving avg approx 30k miles a year in old petrol and old diesel cars, using this method.
If you want to clean all the gunk out of your car, get the tank flushed, and change your fluids and filters.
EDIT: and dont you believe it about fuel being clean. Petrol isn't as bad as it used to be but diesel cleanliness and quality can vary quite significantly.
