I recently bought a new vehicle, and one of the things that surprised me was the need to break in the engine and drivetrain for the first thousand miles.  The salesman that sold me the car mentioned that I shouldn’t bring it above 3,000 RPMs nor use the cruise control for very long trips during the first thousand miles so that the engine could effectively break in.

While this seemed reasonable at the time (even if it was surprising), I did want to learn a bit more about my vehicle, so I did some digging online to find out what was really going on here.  The most reasonable explanation I heard was that, at the end of the day, building an engine is a mechanical process with reasonable tolerances – i.e. it’s not perfect.  Having designed and fashioned my own stuff, this is neither unsurprising nor unacceptable.  As a result of imperfections in the engine, the pistons and rings need time to seat themselves and find the groove that the pistons will travel over the lifetime of the vehicle.  Doing so at or below the average engine speed and allowing that speed to vary during use ensures that those grooves are reasonable.

The thing about this that is shocking to me, then, is actually how long this takes.  So, I thought I would do a little thought experiment.  Over the first 500 miles of my car, I drove an average of 35 miles per hour.  Just as a guess, I would say that my average engine speed was approximately 2,000 RPMs.  Extrapolating that out to 1000 miles:

Or, about three and a half million cycles to find that groove and seat the rings.  That seems like a lot when I think about it in those terms, but an interesting nugget to tuck away in the back of my mind.  I’ve been enjoying learning just a bit more about vehicles over the last few weeks, and this was one nugget I wanted to share.