Back in ye olden days, news car owners were told that, for the first x number of miles, not to drive their cars over xx mph in order to “break in” the engine and transmission.
Is this still true today? (I’ve always had used cars, btw)
I believe the new car i purchased 6 years back had this break-in period.
I’m definately still in my break-in period for my motorcycle (albeit manufactured in India).
Just a couple of anecdotes.
I’ve always wanted a Royal Enfield Bullet.
I bought a 2002 Yamaha YZF-R1 new in 2003. The dealer and the mechanic told me I didn’t have to break in the engine.
I’ve read that for dirt bikes, you only need to let the engine idle for about 15 minutes to break it in. Maybe it’s roughly the same for street bikes, and the manufacturer may do it themselves.
My 2004 Jeep came with directions to drive conservatively for the first 500 miles. IIRC, that meant no towing and no prolonged runs at over something like 5000 rpm. (redline is at 7000)
Thanks to accurate machining tolerances of mass-produced parts, the days of needing to literally wear parts down into fitting together are gone.
Read your owners manual- it depends on the car. AFAIK, no standard car still comes with the special “1000 mile break in oil”, but I can’t be sure. My last car came with a modest set of guidelines, more or less along the lines of “don’t speed, no jackrabbit starts” and such like- all of that being good everyday advice.
Tolerances and technology have improved to the point that much of the “custom fitting thorugh wear” that used to required is no longer needed. One huge improvement is pistons that are made eliptical so that they become round at operating temperature. In the old days they started round and had to wear into the eliptical shape.
That said, there are many examples of items that DO break in over the first 1000 miles or so.
A specific example I am aware of:
Eaton-Dana publishes a break-in procedure for replacement gears used in automotive axles. (Two 25 mile moderatly loaded runs with cool down period after each) Yet new trucks delivered with those same gear sets factory installed do not come with break-in recomendations echoing the advice of the supplier.
Given the expense of a new vehicle why wouldn’t you go easy on it initially?
Going easy at the start will in no event cause any harm. The good it does might not be apparent in the short term, but could well be the difference between a vehicle that becomes high maintainance at 100,000 miles vs. one that seems to keep rolling forever.
My father bought a new Toyota Camry over the holidays, and I told him to drive conservatively for the first thousand miles, but the dealer said the manufacturer breaks in the engine at the factory, so this is unnecessary.
This topic came up on Car Talk, and the brothers disagreed. One of them said to be nice to your car for a while, and the other advocated run it hard from the get go.
A friend of mine recently bought a Mini Cooper S and the advice he got from two different dealerships was to “Drive it like you stole it” to break it in.
He still took it easy the first 1000 miles or so.
What, staying well within the speed limit, making cautious manoeuvers that avoid attention? 
Some cars expect you to drive with a bit of variety the first week or so, i.e. don’t do all highway driving and don’t do all 25 mph around the neighborhood driving. The reason for this is so the engine computer can “learn” how to adjust your car under various conditions for optimal efficiency. Any time you replace or disconnect the battery (so that the computer loses its settings) you are supposed to do the same thing.
Our Saab 92-x owners manual specifies a break-in period of 1000 miles, during which you should not exceed 4000 RPM. This is the same drivetrain as the Subaru WRX, and its manual specifies the same break-in period.
My 2005 Pontiac owner’s manual said basically the same thing: don’t drive long periods at the same speed, no jackrabbit starts, etc. for the first 1,000 miles.
Buy a nice generic Ford or Chevy or Honda or Toyota, etc. and there is no break in period anymore. Can’t speak to exotic cars.
Jim
yep … drive it like you stole it …
expert advice
What’s a break-in? What is it you’re trying to accomplish with this so-called “break-in”? Start with the results that you expect – or with what could go wrong without a break-in – and we can provide an educated, engineering response to the question.
That’s not meant to criticize the question; but there are always questions like this one, or “how often should I change my oil?” or “what’s better for my car?” and so on. Without knowing what you expect out of your car, there’s no one sensible answer anyone can give. I could just as well say, (1) don’t break in your engine; (2) change you oil every 20,000km; and (3) don’t worry about the routine maintenance, and for a great number of people that advice is perfectly suitable to their situation. If you’re trying to join Volvo’s million mile club, then you’ll want more conservative advice. If you say something like you want your car “to last as long as possible,” then you need to plan your goals better! If you plan on trading in your car at 80,000 km, there’s not really anything you need to do to take care of it aside from a couple of oil changes.
Don’t pay for things you don’t expect returns on.
Uh, well, you’re wrong there.
It’s simple, really. Buy a new car. Look in the owner’s manual. Does it tell you that must/must not drive the car a certain way for a certain number of miles.
Question answered.
Lighten up.
I wasn’t looking for advice.
See? No request for advice.
Or, you know, you could rely on the engineering advice given by the engineers who actually designed and built the drivetrain.
Such as what might be found in the owners manual.