Engine "break-in" ...for how many miles?

[awai08]

When I was younger, I was told that new engine required a "break-in" period when new (e.g. 4000-5000 miles), in order to get all the parts to sync together. The break-in process included varying engine speed and/or velocity, and never cruising much past 60mph.

...I did this with my first car (a third generation honda integra) ten years ago, and got many years of reliable and efficient use. Though even today I still wonder; is all this really necessary? And if yes, then how do long uphill runs and acceleration to highway speeds factor into the break-in process? I ask b/c even normal acceleration to highway speeds (i.e. brisk enough to keep up with traffic) seems to keep the 1.5L engine quite busy.

[apriusfan]

<div class='quotetop'>QUOTE(awai08 @ Sep 3 2007, 11:18 PM) [snapback]506653[/snapback]</div>

When I was younger, I was told that new engine required a "break-in" period when new (e.g. 4000-5000 miles), in order to get all the parts to sync together. The break-in process included varying engine speed and/or velocity, and never cruising much past 60mph.

...I did this with my first car (a third generation honda integra) ten years ago, and got many years of reliable and efficient use. Though even today I still wonder; is all this really necessary? And if yes, then how do long uphill runs and acceleration to highway speeds factor into the break-in process? I ask b/c even normal acceleration to highway speeds (i.e. brisk enough to keep up with traffic) seems to keep the 1.3L engine quite busy.
[/b]

You should have a lively debate going in no time. Regardless of what you decide to do, the ICE is going through a break-in process. You can confirm the break-in process is occurring with used oil analysis. The variable with the Prius' ICE is that the ICE is not always on. So, you have to extend the break-in period based on how frequently your car's ICE is on. Enjoy your new car!

[bwilson4web]

A suggestion, most of us have 1.5L engines. The editing function works well.

As for 'break-in', this is a 'drive by wire' car. You can avoid exteneded high power settings by keeping the vehicle speed under 65 mph for a while but there will still be excursions based upon normal driving. Really, the control computers are running everything and our accelerator inputs are 'interpreted' rather than directly driven.

GOOD LUCK!
Bob Wilson

[Rae Vynn]

When we did the first oil change, at 5050 miles, the used oil looked pretty awful.
DH pulled the dipstick at the last gas fill-up, which was at 7200 miles, and the Mobil 1 has become "visible" on the dipstick, slightly yellow, but not at all the sludgy-looking like the original (dino) oil had.

My guess, based on this entirely unscientific "used oil analysis", is that the first 5 or 6 thousand miles is a typical break in period, and that you should drive the car in as many different types of conditions as possible... up hills, down hills, highway speeds, city speeds, rambling back road speeds, starting, stopping, and cruising.

I recommend an extended road trip! It helps you learn the car, while it breaks in the engine

[awai08]

Thanks for the replies!