my car has 103000 miles on it. Im guessing the plugs/wires are original. There are currently no problems with the car. Could it hurt anything to leave these plugs/wires in for anothet month or should i change the plugs/wires asap?

Also, the same deal with the coolant and probably the tstat. Should i do this maintainence asap?

thanks

 

The plugs/wires are not going to hurt anything, especially since you say the car is running ok.

Coolant does lose it's corrosion protection properties over time. That should be changed. Change the thermostat if you want, but if it is working, why mess with it?

 

What will happen if you never change your plugs? I dont know because i have never done it.

 

You'll eventually foul em and your performance will diminish but certainly won't damage the engine.