Dear Car Talk:
I've always been told not to run my gas tank to empty. Not because I might get stuck, but because the fuel pump will pick up trash at the bottom of the tank and cause the filter to clog up.
Is this still true? Or is it no longer true for newer models? Remember, not all of us drive newer cars. -- Ann
Well, if you're still driving your 1937 Duesenberg, Ann, it's probably good advice. But if you're driving a car that was made within the past four or five decades, picking up "junk" at the bottom of the tank is not something you have to worry about.
There are several reasons why it's a nonissue. First, the pick-up tube itself has a fine-mesh sock on it. That allows liquid gasoline to pass through, but stops any debris large enough to damage the pump or the injectors.
I suppose if you had enough crud in your tank, you could conceivably clog up that sock. But you'd have to have the wreck of the Edmund Fitzgerald in there to do that. Plastic gas tanks also have made a difference. They're very common in cars now. And increasingly common at gas stations, too, where the fuel is stored. So while old steel tanks could rust and produce flecks of metal when they get old, plastic is forever -- fortunately and unfortunately.
And, finally, gasoline itself has gotten cleaner. When manufacturers made a massive shift to fuel injection, starting in the 1980s, many of them demanded that the oil companies make cleaner fuel.
They didn't want the tiny passages of their expensive new fuel injectors to get clogged up. And they especially didn't want to have to replace them for customers under warranty.
So a bunch of manufacturers created their own fuel standard, called "Top Tier Detergent Gasoline." It had to have extra detergents and no metallic additives. And most major oil companies complied and made the stuff.
Then, over the past dozen or so years, thanks to EPA regulations, gasoline has gotten cleaner still.
We used to routinely see fuel filters plugged up after 30,000 miles. These days, we hardly ever see that. In fact, after we replace a fuel filter, we'll sometimes cut open the old one, just out of curiosity. And usually there's more debris on the meatball sub we bought for lunch than there is in the fuel filter.
So you're not going to suck up any junk from your fuel tank if you run it to empty these days, Ann. You might get stranded and robbed by highwaymen. But your injectors will be fine.