Q: Is 93 octane gas only for race cars?

A: No. A fair number of vehicles have high-performance engines that call for 93-octane gasoline. But most do fine with 87- or 89-octane fuel. Sometimes older engines need all the help they can get. The higher the compression ratio with older cars, the more need for a higher-octane fuel. If the car performs better with 93-octane, use that grade of gas. It won’t hurt the engine. Race cars? They like 100-plus octane fuel.

Q: How much extra fuel is burned when using air conditioning?

A: It is estimated that the use of air conditioning in a typical car reduces fuel economy by one to two miles per gallon. For larger cars, or when traveling in extreme heat, air conditioning cuts fuel economy up to four miles per gallon.

Q: Can spark plugs really go 100,000 miles before being changed?

A: I have heard of spark plugs found seized in cylinder heads of vehicles with as little as 60,000 miles. It took over four hours’ labor just to remove the plugs. There are documented cases where it was necessary to remove cylinder heads just to get the plugs out. Experienced mechanics suggest that to maintain peak performance, spark plugs should not be run longer than 60,000 miles, even though they continue to fire. Car buyers should take those “100,000-miles” marketing claims of manufacturers with a grain of salt.

Q: How do you know how much air to put in tires?

A: Inflate tires according to the vehicle manufacturer’s recommended inflation pressure found in the owner’s manual or on places such as the door post and glove box door. As the Tire Industry Safety Council puts it: “Just because the speedometer in your vehicle measures speeds up to 120 m.p.h. doesn’t mean the manufacturer is suggesting 120 as a recommended cruising speed. The same applies to air pressure limits stamped on the sidewall of your tires.” Unless you load your vehicle to its maximum carrying capacity, using the maximum pressure listed on the tires will result in a terribly hard ride and may adversely affect steering control.

Q: How should you use antilock brakes in and emergency?

A: Firmly apply and maintain continuous pressure on the brake pedal while continuing to steer away from obstacles. Anti-lock brake systems use sophisticated sensors to automatically pump the brakes up to 18 times per second. Even racer Mario Andretti can’t move that fast. Steer normally. The main benefit of an anti-lock brake system is that it doesn’t allow the front wheels to lock, which causes loss of steering control. “Most importantly, don’t jerk the wheel,” says David Wills, president of the AAA Foundation for Traffic Safety. “That’s a natural thing to do, but with ABS the car will respond to steering input and go off to the side” and not slide into an accident.

Serving Jacksonville Since 1991