What exactly to do during BreakIn Period

[360cubes]

Originally Posted by Loren

You do need to let the engine rev SOME to break in properly.

Well said!

I've test driven new cars as if I've owned them for ten years and was late for a track meet. Some higher RPM use will be fine. Drive around town in 3rd gear and use 4th at lower highway speeds (55mph) for a few miles. As it was mentioned, you're not only breaking in the engine but the transmission as well. You want to make sure everything works fluidly and is sound in case you had to press the pedal down to get away from someone (a rare emergency getaway, like SEMI losing brakes going downhill!). It won't hurt anything and be SURE to get your oil changed around 1000miles, this will help prolong engine life as the filter may not contain all the metal particles left behind accidentally from the manufacturing process.

[R2D2]

I agree with Loren, MadMax and 360cubes-you need to load the engine enough to seat the piston rings early on. I don't know why engine manufacturers insist on people babying engines for the first 1k. In my experience this is the wrong thing to do. I drove mine off the lot like it was stolen. Not being abusive, just generating enough pressure to force the rings out against the cylinder walls to get a good seat.

360cubes- excellent point on changing the factory oil at 1k. This has always been my practice as well. Oil analysis on factory fill can be pretty nasty but metals/silicon usually trend down fairly quickly after the initial oil change.

[YarisSedan]

The most of the breakin occurs in the first 100 miles already so theres not much more you can do. Just try to avoid constant speeds like long freeway driving. This may cause glazing on the cylinder walls. Otherwise just drive it like you normally would. A good mix of speeds is best. Occasional high revs but not redline is good.