Corp. surveyed its team of Automotive Service Excellence (ASE)-certified Master Technicians, which has more than 840 years of combined experience repairing cars, to reveal the top 10 maintenance mistakes car owners make with their vehicles.

The results:

  1. Putting off recommended/scheduled maintenance
  2. Ignoring the "check engine" light
  3. Not changing the oil, or not having it changed on time
  4. Not checking tire pressure
  5. Neglecting coolant, brake, transmission and other fluid services
  6. Continuing to drive when the vehicle is overheating
  7. Not changing fuel and air filters
  8. Having unqualified shops service your vehicle
  9. Using generic aftermarket parts instead of original equipment manufacturer (OEM)-quality parts
  10. Trying to service your own vehicle

No. 3 in the top 10, "not changing your oil," was listed by technicians as by far the single most damaging car maintenance item that customers neglect. Dirty oil ruins today's high-tech engines, CarMD said. Camshaft actuators can freeze when restricted by dirty oil, and a faulty camshaft actuator can in turn cause the "check engine" light to illuminate, resulting in complete engine failure if ignored for too long.

Simply following the factory-recommended oil change schedule helps vehicle owners avoid this problem.

Ignoring the "check engine" light is another example of how putting off repairs on a small problem can escalate to an expensive repair, CarMD said. According to the CarMD Vehicle Health Index, the most common reason for a "check engine" light is a faulty oxygen (O2) sensor. A dirty air filter, which usually costs less than $20 to repair, can result in an O2 sensor failure, which can cost almost $250 to repair and can result in gas mileage reduction, can cause the vehicle to misfire and eventually result in the need for an expensive catalytic converter replacement (which can cost mroe than $1,000 to repair).

CarMD offers a free online service, available at, where anyone can see the most common problems for a specific vehicle, as well as how it scores in terms of reliability against other vehicles on the road.