is it really necessary to change my spark plugs after each 35,000 miles? that is what the owners manual of my 94 Toyota says to do?

i put in the OEM spark plugs last time around 2years and 35,000 miles ago....they are not the new modern ones....but i just dont know if it is worth it or not....should i? why or why not?

btw, this is on a 3.0 liter V6 Toyota engine (VZE model)


what about spark plug wires and distributor cap and rotor too?  I changed those too around same time as i did spark plugs

4 Answers

  • 10 months ago
    Favourite answer

    If you'd like to replace spark plugs every 100,000 miles put a set of NGK or Denso Iridium spark plugs in the motor.

    Regular copper OEM plugs only last 30,000 miles.

    Source(s): Mitsubishi Master Tech
  • 10 months ago

    Toyota would put Denso plugs on one side and NGK's on the other. Regular bare tipped plugs. And at 30,000 miles they were ready to be changed. I would go with the original. They were in there for a reason. Unless you are smarter than their engineers. 

  • 10 months ago

    Conventional spark plugs often last only that long. You can try cleaning and gapping them for longer use. If the plugs aren't getting oil or carbon fouled that can get you a little more life from them.

  • 10 months ago

    How did your last set of plugs look after 35k miles, that should give you a hint.  Never go 100K miles, although the plugs may still work they are getting harder for the coil to fire and put more strain on it, I go 50K miles on my plugs as a plug is much cheaper to replace than a coil pack.  If you keep your car for 150K miles you only have to change them twice. if you can't afford to change them after 50K miles perhaps you should not have a car.  I think wires depend more on age, you can look at the cap and rotor to see how the contacts are holding up.  If they look burnt or worn down change them.

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