Winter Driving Tips

Car Talk Winter Driving Tips
Check the cooling system.

Make certain the antifreeze will protect your car at the winter temperatures you'll experience in your area. For most areas, you'll need a 50-50 mix of coolant to water. You may think, "I'll be extra good to my car, and give it 100% coolant." Guess what? You're wrong. The 50-50 mix has a lower freezing point. Not only that, but 100% coolant is less able to transfer heat away from your engine, and has been known to cause such nasty things as melted spark plugs of engine failure under the wrong circumstances.So, mix it up!

Protection Freeze-up Protection Boilover Protection Corrosion Protection
Minimum 50% anti-freeze
50% Water
-34ºF +265ºF Exceeds all ASTM and SAE standards for corrosion protection
Maximum 70% anti-freeze
30% Water
-84ºF +276ºF

You can check the freeze rating of your car's coolant yourself with a little device that you can buy in an auto part store for a couple of bucks. With it you suck up a little of the anti-freeze from the radiator - or the overflow container - and see how many of the little balls float. It's cute. If this is beyond you, most real gas stations will do it for you in a couple of minutes. By the way, having good coolant in your engine is very important because if the coolant freezes, it expands, and it's bye-bye engine block. And that means bye-bye to the 50-inch plasma TV you've been saving up for.

But that's still only half the story. The other primary function of antifreeze is to keep your cooling system from rusting. The rust inhibitors in antifreeze break down over time and need to be renewed. So, at a minimum, change your engine's coolant at the interval recommended by your manufacturer. Besides, draining out the coolant and refilling the system also removes dirt and rust particles that can clog up the cooling system and cause problems, regardless of the season.

There are two primary types of coolants available on the market today. The first is traditional, green-colored antifreeze, which can be used in any car. The second is a newer, long-life coolant, which comes in a variety of colors. It should only be used in recent-model cars because it may damage some of the engine gaskets in older cars. If you're not sure whether your car uses the new or old-style antifreeze, check with your manufacturer.

In a pinch, the new and the old coolants can be mixed- but if you do that, you should drain the cooling system next time your car is in for service. The rust-inhibiting additives in the two coolants can actually counteract each other and, over a long period of time, allow the cooling system to rust. It takes a long time for this damage to occur, so you don't have to rush home and drain the system. But do take care of it promptly, so you don't forget and find yourself slapping your credit card down for an engine rebuild, a few years later.

Finally, if you're driving a General Motors car that uses their Dexcool coolant, we'd suggest you pay extra attention to flushing your cooling system on a regular basis. Several years ago, early formulations of Dexcool would form sludge after mixing with air, clogging cast-iron cooling passages and generally wrecking havoc on engines. GM seems to have fixed the problem, but why take a chance? Keep an eye on it.