"I'm dealing with a situation where a customer drove their car for 90,000 miles without ever having the timing belt replaced, even though the car manufacturer suggested changing it at the 60,000 mile mark," says Eric Currin, a mechanic in Georgia.
"The timing belt slipped in three places. The car cut off. When the customer tried to restart the car, they bent several valves. So what would have been a $600 job to replace the timing belt has turned out to be a $2,000 job to replace the belt, valves and other related parts."
Cost of skipping: Damaged valves and pistons.
4. Annual brake checkup
Brake disc pads and shoes eventually wear down. Checking your brakes annually allows you to plan ahead and know when it's time to replace them. By contrast, neglecting regular brake work could eventually lead to more costly rotor or drum replacements.
"If you ignore your brakes, then you'll just continue to wear down your discs (the friction part of the brakes that wear with normal driving)," says Reed. "If the discs go down metal to metal, you could gouge your rotors. Then, what would have been a $150 brake job (to replace discs) could turn into a $300 brake job to replace rotors."
Brake inspections can also help a technician identify a problem that doesn't involve brake disc pads at all.
"There could be a lack of brake fluid or a leak in the master cylinder that's under the hood," says Sclar.
You might never know unless you have the brakes checked.
Cost of skipping: Expensive rotor or drum replacement.
5. Replacing PCV valve regularly
The positive crankcase ventilation, or PCV, system helps regulate the flow of fumes around the engine. It includes hoses as well as a PCV valve, which should be replaced at recommended intervals.
"The PCV valve helps protect the seals and gaskets on an engine. It keeps them from getting corroded and cracked, which can cause oil to leak," says Currin. "The cost for a replacement PCV valve is just a few dollars, plus a minimal cost of labor to install it. But if you don't get it replaced when necessary, the seals could leak.
"If you do have a leak, it costs over a hundred bucks to replace a valve cover gasket. If it gets really bad and the head gasket starts to leak, you could be faced with thousands of dollars for repair bills."
Cost of skipping: Leaking head gasket, failed emissions test.
6. Changing spark plugs and filters
Do you live in a state that requires your car to pass an emissions test? If so, failing to maintain your car could lead to a huge repair bill to bring the vehicle into compliance.
"The average repair bill is somewhere between $335 to $350 to fix a problem that causes an emissions test to fail," says Rich Parlontieri, CEO of Speedemissions, a vehicle emissions testing/safety inspection company with emissions testing locations in St. Louis, Salt Lake City, Houston and Atlanta. "Common causes of failed emissions tests include faulty oxygen sensors, air flow monitors and catalytic converters."
States may require drivers to spend between $400 and $855 to attempt to fix their own cars before the state finally grants them a waiver to bypass the emissions test, Parlontieri says. Basic maintenance can prevent many of these problems from occurring in the first place.
"The best way to improve the odds of passing an emissions test is to maintain your vehicle. A well-maintained engine is usually a clean engine as far as emissions are concerned," says Parlontieri.