I recently bought a new car and have put around 800KM so far on it. The manufacturer recommends that I "break in" the car's engine properly by driving gently for the first 1000 to 1200KM.

I have been doing just that, driving it very gently and making sure not to go over 2500rpm, but last night, I parked the car and kept it on idle for around 2.5 hours with the AC running inside.

I guess my question is whether I did any damage or "disrupted" the break in process since the piston rings may have not been "seated properly" yet during the first 800KM that I have done so far on the car.

FYI - I have to take the car for its first service and check up when it hits 1000KM as part of the "new vehicle" check up.. I guess they will be changing some fluids there.

Thank you.

  • 1
    About the worst way to treat any car is to leave it sitting idling. Guess why they said "driving gently"?
    – Solar Mike
    Oct 10, 2021 at 8:06
  • Thanks for the insight Mike, you're always available to answer my qs !:p Oct 10, 2021 at 11:30
  • We don't know what engine size you have, and 2500RPM is very different in a 3L diesel compared with a 1L gas engine, but "driving gently" doesn't mean "always using low revs", it means "not flooring the gas pedal when you don't need to." In fact running at constant RPM for long periods is a bad way to run in any engine.
    – alephzero
    Oct 10, 2021 at 12:06
  • "I guess they will be changing some fluids." Is this a modern car, or a 30-year old design? My last new car had its first oil change at 17000 miles (on long-life synthetic, otherwise it would have been 10000). And we don't "break in" cars any more - they are not horses. Also, you shouldn't do those initial miles all at the same speed, so if you do a lot of motorway running, don't just sit at the speed limit. Oct 10, 2021 at 15:54

1 Answer 1


Idling for a long time isn't ideal. But you haven't at this point in the process done anything catastrophic or anything close to it. Machining processes have dramatically improved over the last couple of decades. This is why we've seen break in procedures change over the years. Don't let this bother you, there is almost no chance that you did detrimental damage to your car. Drive on and enjoy.

  • Appreciate it Jupiter; never idling the engine this long next time for sure! :p Oct 10, 2021 at 11:29

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