Maybe you have a story like this: A friend brought her car in for a $30 oil change and wound up paying $3,000 for unrelated "urgent" repairs that turned out not to be so urgent. Still, the top things a mechanic might suggest are fluid changes, tire rotations and new brake pads—which you may genuinely need, says Austin Davis, author of What Your Car Mechanic Doesn't Want You to Know
and founder of MyHonestMechanic.com
. By letting the mechanic, who's already got a good look at your engine, check out key areas, you can save yourself an extra trip to a dealer or a surprise problem on your next road trip. Davis recommends keeping these facts in mind: Transmission fluid should be changed every 50,000 miles, the power steering fluid once in the car's lifetime (roughly 100,000 miles), and your tires should be rotated every 9,000-10,000 miles. "The front brakes need to be replaced about twice as often as the back ones, because that's where the stopping power is," he explains. If a mechanic urges you to change them, ask how thick the brake pad is compared to its metal backing—if the pad is thinner than the backing, it's time to replace them.