Cold is a stopper. In some pans of the country, the harshest day of the year is practically a traditional holiday-one that's most widely observed by cars. The drivers, unfortunately, still bundle up to give 'er a try. Not until the grinding moan of the starter has faded to a series of pathetic clicks will we admit that no creature with ordinary sense (a car, for example) would go out on a day like this for any reason other than to fetch more firewood.
We at MOTHER don't mind people taking an occasional unofficial holiday, but the premise bothers us. Why should the car decide when we take the day off?
What the Cold Does
Cold weather makes the engine hard to start for two main reasons. First, oil thickens when it's cold, which increases friction and makes it harder for the staner motor to spin the engine. Cold also slows the chemical reaction in the car's battery, reducing its power output. Battery output is usually rated at 77 degrees Fahrenheit, below which starting power drops drastically. As shown in Figure I, (See the car diagrams in the image gallery) at 5 degrees Fahrenheit a fully charged lead-acid battery has only half its rated amp-hour capacity. You can ensure that your car will start in the worst weather by keeping the engine or the battery, or both, warm. But before we discuss some of the ways - short of building a heated garage - to keep the underhood cozy, let's review basic maintenance.
Send your car into winter with its edges finely honed by giving it a tune-up in the late fall or early winter. When the engine is struggling against thick oil and a weak battery, it needs ignition and fuel systems that are in top shape.
Always switch to a lighter-weight oil in the winter. In general, a IOW30, 40, or 50 multigrade oil is a good choice, but follow the manufacturer's recommendations. Even if you use a wide-range, multigrade oil year-round, change it before cold weather sets in.
Viscosity (thickness) increase is one of the ways that oil deteriorates with use.
It's vital to keep the battery's terminals clean and securely fastened to prevent resistance. It's also helpful to wash the battery's case (particularly the top) with a baking soda-water solution whenever any deposits appear. These accumulations can drain your battery by conducting current directly from the positive terminal to the negative one or to the chassis. And be sure to inspect the connection of the negative wire to the car's engine block or frame. This junction is just as likely to loosen or get dirty as the one on the battery itself.
Check the electrolyte level and the specific gravity of each cell in the battery at least once a month. If electrolyte is needed, add soft water. You can get a battery hydrometer for testing specific gravity at any auto parts store for less than $5. Test the battery after it's been sitting overnight without being charged and before you add water or try to start the engine. Use the data in Figure 2 to correct the specific gravity reading for the electrolyte temperature, which in this case you can assume to be the same as the air temperature.