Paul Brand: Fuel line antifreeze not all hype

Q Isn't using a gas line antifreeze these days ridiculous? All our "oxygenated" gasolines are at least 10 percent alcohol already.

What possible good would adding an additional 12 ounces of alcohol do? I think all the manufacturers and dealers of these products should be exposed for cheating motorists out of good money for a product with no value.

A Ah, don't you just love a good conspiracy? You have a point that drivers today have little need for gas-line antifreeze additives, but I don't agree that these additives have "no value."

Technically, there is a significant difference between the alcohol in gas line antifreeze/de-icer and the alcohol in our gasoline.

Most fuel line additives are based on isopropyl alcohol -- stay away from any methanol-based de-icers, they can corrode fuel system components -- while our gasoline contains ethyl alcohol.

Isopropyl alcohol will combine with water and remix any phase-separated water/ethanol to accomplish two things: First, it will prevent water from freezing anywhere in the fuel system; and second, it will carry the "mix" through the system into the engine to burn. This prevents the moisture and alcohol from sitting in the bottom of the fuel tank waiting to leave you stranded by the side of the road.

You are correct that the ethanol in our fuel will mix with water and thus function as a gas line de-icer, but any significant percentage of moisture in the gasoline can cause phase separation because the ethanol would rather bond with water than with gas. I see some benefit in adding a single small bottle of isopropyl at the beginning of the cold weather to carry any existing moisture through the system, but continuously adding these products with each tank of fuel can result in too much total alcohol in the gasoline.

Bottom line: If you don't want it, don't buy it.

Q During a Thanksgiving road trip to Nebraska with my girlfriend, we hit a deer with her 2007 Ford Focus. The vehicle hit the deer in the soft part of the animal's midsection, and we drove right over it without slowing down at all. A visual inspection found no damage to the car.

I think that the front wheels are slightly out of balance, but what worries me is the airbag system. At the time of the collision, the airbags did not deploy.

And now the airbag trouble light. The car made it the rest of the trip without issue. Do you have any insight as to why the airbags did not deploy and what the trouble light could be indicating?

A Because the vehicle did not "slow down at all" as it ran over -- not "hit" -- the animal, the airbag sensors did not experience a significant rate of deceleration. Unless the deceleration rate is high enough to potentially cause injury to the vehicle's occupants, the restraint control module doesn't recognize a deployment event.

The cause for the airbag warning light might be damage to the forward crash sensor or its wiring harness, mounted on the radiator support at the front of the vehicle. Regardless, you should have the dealer scan for restraint system fault codes as well as inspect the vehicle for any hidden damage.

Happy holidays and have a safe new year!