The 100,000 Mile “No Tune-Up” Myth

What the car makers are really talking about are 100,000 mile spark plug change intervals — which does not include the need for other maintenance such as oil and filter changes or other repairs that might be needed during the life of the vehicle.

If you think you can get away with gas-and-go driving for 100,000 miles without spending a dime on maintenance or repairs, you might find the hard way that lack of proper maintenance can be very costly.

Regular oil and filter changes are still necessary to maintain proper engine lubrication. (Oil Change) .

Today’s 100,000 mile tune-up interval also skirts around the issue of fuel and air filter replacement, too.

Repairs are also inevitable regardless of what the tune-up interval is supposed to be. It’s pretty unlikely that a set of front disc brake pads will go 100,000 miles in city driving — 20,000 to 30,000 miles is a more realistic figure.

The same goes for belts, hoses, the battery, water pump, exhaust system and many other parts.

No vehicle that’s yet been built can even come close to going 100,000 miles without needing some type of maintenance or repair.

Tune-Up Checks

Any tune-up today should start with a list of performance checks  determine the engine’s overall condition. These should include:

  • Battery voltage (very important with all of today’s onboard electronics). Charging voltage.
  • Power balance or dynamic compression (to identify any mechanical problems such as leaky exhaust valves, worn rings, bad head gasket, bad cam, etc. that could adversely affect compression and engine performance)
  • Engine vacuum (to detect air leaks as well as exhaust restrictions)
  • Operation of the fuel feedback control loop (to confirm that the system goes into closed loop operation when the engine warms up)
  • Scan for fault codes (to verify no fault codes are present, or to retrieve any codes that may be present so they can be diagnosed and eliminated)
  • Hoses and belts visually inspected.
  • All fluids (oil, coolant, automatic transmission fluid, power steering fluid and brake fluid) are inspected to make sure all are at the proper level, and that the appearance and condition of each is acceptable.

If the tune-up checks find no major faults, the following items are replaced for preventive maintenance:

  • Spark plugs (gapped to the correct specs, of course).
  • Rotor and/or distributor cap (if required)
  • Fuel filter; Air filter; PCV valve and breather filter
  • Check and adjust (if required on older vehicles) ignition timing, idle speed and idle mixture; O2 sensor(s).

Tune-ups may not be fun, but they are essential.  Preventive maintenance is essential for the good health of your vehicles.