CarTalk.com Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Gas line anti-freeze

With the addition of ethanol now to gasoline is it still necessary to use a gas line anti-freeze such as “Heat”?

Not if you have a modern car. In modern fuel systems the gas is highly pressurized all the way through the lines right to the injector orafices. This makes gas line freeze up pretty much a thing of the past.

Good question! In theory the ethanol should do the job. I never used gas line anti-freeze more than once a year anyway, so it’s sort of a moot point for me.

Maybe a chemist out there will give us a definitive answer.

Not a chemist, but I did stay at a holiday inn express last night :slight_smile:
The gas line antifreeze I have in stock is isopropyl alcohol and that may make a difference. You wouldn’t normaly need to add routinely as per Mountainbike, but only when a water issue comes up such as water in the gas you buy or condensation in the tank.

Tough question. The ethanol is added to make the water, ethanol, and gasoline mix. If the gasahol is relatively free of water, it should take care of water introduced by condensation in the fuel tank. The trouble is that the ethanol makes the fuel more readily absorb water from the air.

The simple answer is a flat-out “No!” Modern cars using modern gasolines simply don’t freeze their fuel lines.

Occasionally you run into someone who insists it happened to his neighbor’s uncle’s work buddy. Ask how he knew it was a frozen fuel line rather than some other cold-weather problem.

Save the Heet or Dri-Gas or related product for known water problems, such as when you go through the car wash with the fuel cap off and the filler door wide open. (I’m not making this up. This forum gets this problem maybe one a month.) Don’t waste your money on using it for regular winter treatment.

The 10% ethanol found in virtually all gasoline is more than enough to scavenge any moisture and prevent fuel line freeze-ups…

Ethanol does indeed absorb moisture. The problem is that ethanol will phase seperate out of gasoline if gas sits over an extended period of time. You then end up with a top layer of ethanol alcohol, a layer of water below that, and the gasoline making up the bottom layer. Isoprophyl alcohol on the other hand also absorbs moisture, but it doesn’t phase seperate out of the gasoline. That’s why it’s used as a fuel system moisture treatment.

And contrary to belief, the fuel system on a modern car doesn’t remain under constant pressure after the engine is turned off. The pressure slowly bleeds off. But a column of fuel is left in the fuel system so that when the fuel pump restarts, fuel pressure is immediately restored.

Tester

Except on those cases where one has a leaky injector that allows air to enter the lines and displace the fuel as it drains out…

I can’t find the post I made 5 minutes ago on why modern fuel systems make drygas obsolete to amend it, so I’ll add to it via a new post.

In addition to modern systems being a sealed fully-filled line operating under high pressure, multiport systems have the injector right behind the intake port, right behind the valve, a nice toasty-warm area. Carburators, in adddition to having the stuff that you’ll see in my invisable post, were located remotely from the heat of the engine.