Q: A friend has offered me winter storage space in her garage for my summer car, a 1988 Mazda RX-7. A generous offer indeed! Should I worry that the garage is unheated? Are there precautions I should take, such as removing the battery or occasionally starting it and running it throughout the winter? What about those gasoline additives? I've never used those things before, should I? - Geno G., Minneapolis
A:The biggest concern in an unheated garage is making sure your antifreeze is at proper mixture. A cheap tester from any auto parts store can put your mind at ease on that issue. Open the radiator cap when the engine is cool and make sure the fluid is topped up, too. (Add 50 percent water, 50 percent coolant, if what you're pouring is not already "pre-mixed.")
Other things that will happen as the car sits: the most volatile portions of the gasoline will evaporate, degrading its quality over our long winter. Gas stabilizer is a good idea to keep the gas from getting gummy in the fuel system. The usual approach is to add the stabilizer based on your gas tank's capacity, filling up the tank to assure correct ratios. Might be tricky in January finding a day with clear, dry roads when you can sneak out and do that.
Batteries also take a beating over the winter. A trickle charger is a good way to keep it alive and well, but if that's not workable, you can remove the battery, charge it up and keep it in a warmer environment, such as your own basement-you can put the trickle charger on it in the basement. If that too is impractical for some reason, going over and starting the car every other week or so and letting it run until the engine warms up will help keep the battery alive. (Obviously, you'll have the car outside to do this; never run an internal combustion engine in an enclosed space!)
Your tires will also lose pressure over the winter. Flat spotting is not the risk it was long ago, but remember to fill them up when you return the car to the road in the spring. Check them periodically and top them up too, if they look low over the winter.
Q:We have a 2005 Toyota Camry with the four-cylinder engine (82,000 miles). I just read your article about the Prius and differing mileage. I check my mileage on long trips and between fills. When traveling through Wisconsin towards Chicago I sometimes can do as good as 36 mpg and sometimes heading to Denver it is lower. This is a long shot but it could be elevation-related as you slowly drive up about 4,000 feet to the Denver area. Another thing I do is wash and wax the car before a long trip if possible and I even put Rainex on all the windows to make the car slick. A factor with the Denver trip is the 75 mph speed limit in Nebraska and Colorado, which does not help the mileage, as opposed to when we travel 65 mph in Wisconsin So the speed limit may be the reason. I think the tire pressure reads 29 listed on the door and I fill the tires to 35, which helps. I have heard of friends telling fibs to a car owner to give them a bad time and even employees who put extra gas in a coworker's tank and conversely siphoning some to make them think they were getting better mileage and sometimes worse mileage. - Paul W., Mound
A:Altitude used to be a bigger factor, when cars lacked computer controls to adjust air/fuel mix to compensate for higher altitude's lower oxygen content. Still, a long climb takes more horsepower and more fuel than steady driving on the flat. Overall speed also affects mileage because wind resistance increases exponentially - the faster you go, the harder the wind tries to stop you. Everyone should notice a reduction in economy at 75 compared to 65 mph. Rolling resistance is also a factor, though there's debate in the car community over how much it matters. The biggest variable from your list is any friends secretly adding gas to your tank - or (non)friends taking some back out. I'm willing to suffer the first of those injustices regularly. Thanks for your comments. Good food for thought.