Myth: Let your engine warm up for several minutes before driving

Reality: That might have been good advice for yesteryear's cars but is less so today. Modern engines warm up more quickly when they're driven. And the sooner they warm up, the sooner they reach maximum efficiency and deliver the best fuel economy and performance. But don't rev the engine high over the first few miles while it's warming up.

Myth: After a jump-start, your car will soon recharge the battery

Reality: It could take hours of driving to restore a battery's full charge, especially in the winter. That's because power accessories, such as heated seats, draw so much electricity that in some cars the alternator has little left over to recharge a run-down battery. A"load test" at a service station can determine whether the battery can still hold a charge. If so, some hours on a battery charger might be needed to revive the battery to its full potential.

Myth: If regular-grade fuel is good, premium must be better

Reality: Most vehicles run just fine on regular-grade (87 octane) fuel. Using premium in these cars won't hurt, but it won't improve performance, either. A higher-octane number simply means that the fuel is less prone to pre-ignition problems, so it's often specified for hotter running, high-compression engines. So if your car is designed for 87-octane fuel, don't waste money on premium.

Myth: If the brake fluid is low, topping it off will fix the problem

Reality: As brake pads wear, the level in the brake-fluid reservoir drops a bit. That helps you monitor brake wear. If the fluid level drops to or below the Low mark on the reservoir, then either your brakes are worn out or fluid is leaking. Either way, get the brake system serviced immediately. You should also get a routine brake inspection when you rotate the tires, about every 6,000 to 7,000 miles.

Myth: Engine oil should be changed every 3,000 miles

Reality: Despite what oil companies and quick-lube shops often claim, it's usually not necessary. Stick to the service intervals in your car's owner's manual. Under normal driving conditions, most vehicles are designed to go 7,500 miles or more between oil changes. Changing oil more often doesn't hurt the engine, but it can cost you a lot of extra money. Automakers often recommend 3,000-mile intervals for severe driving conditions, such as constant stop-and-go driving, frequent trailer-towing, mountainous terrain, or dusty conditions.

Maintain Your Air Conditioning

If you've ever lost your air conditioning on a hot summer day, then you know what a big difference a little cool air makes. The best way to tell if your air conditioner has a problem is if it can't generate or maintain air temperatures that are 50 degrees Fahrenheit (10 degrees Celsius) below the ambient outside air temperature.

The most common cause of a malfunctioning air conditioning unit is a low level of refrigerant. This could be caused buy a leak somewhere in the system. Since modern air conditioning systems are complicated creatures, it's best to have a professional check out the problem.

The air conditioning maintenance industry has changed a lot since 1994, when the Federal government outlawed the use of a refrigerant called R-12, known by its brand name Freon. In the past, if your air conditioner wasn't blowing cool air, you'd head down to the service shop, they'd top your car off with a little Freon and you'd be on your way.

The problem is that Freon, a chlorofluorocarbon, is extremely destructive to the ozone layer. Most people needed Freon refills because they had leaks. By simply refilling the leaky air conditioning units, millions of pounds of Freon were entering the atmosphere every year.

If your car was built before 1994, then you need to have your refrigerant checked out by a licensed professional who knows how to dispose of or recycle the material. In some states, it's illegal to refill a leaky system with R-12. However, even older cars can be easily retrofitted to use the newer, safer type of refrigerant called R-134a.

Check the Coolant and Radiator

Cars are designed to run hot, but there's a limit to how hot they should run. A combustion engine is most efficient at around 200 degrees Fahrenheit (93 degrees Celsius). But if an engine is allowed to get too hot, moving metal parts can actually start to melt and fuse together, causing a variety of internal problems for your engine -- and, you guessed it, a hefty repair bill.

Luckily, all modern cars have an ingenious cooling system that uses a chemical coolant, called antifreeze, and a series of pumps, hoses, thermostats and fans to keep the car at its optimal running temperature. But any problems with this system -- low coolant levels, cracked hoses, loose or broken belts, a leak in the radiator or even a loose or missing radiator cap can cause your car to overheat and break down.

The summertime is tough on cooling systems. Sitting in traffic on a hot day is one of the quickest ways to overheat your car. This is because there's no air flowing across the engine to help keep it cool. A well-tuned cooling system can take long idles in hot weather, but if you have low coolant levels or a busted fan belt, your engine temperature is going to go up -- and fast.

Check under the hood and make sure that your coolant levels are fine. The general rule is to flush your radiator and add new coolant at least every two years. Flushing the radiator is done with a special chemical that cleans debris and build-up on the inside of the radiator. For summer driving, coolant should be added as a 50/50 mixture of antifreeze and water. You can even buy premixed coolant so you don't have to bother with the measurements.

If you see a small puddle of coolant under your car when it's been parked for a while, then you have a coolant leak. Take it to the service station as soon as you can to get your system checked out.