Patman
Staff member
I have 152,000 miles on the original plugs in my Civic!
But the engine runs smoothly at idle and at full throttle and my gas mileage is insanely good (49 MPG average over the last 4000 miles!) I might as well leave it alone for now. I know of another Civic owner who has 250k on his plugs! So I have a ways to go 

