Engine run-in, still required or recommended?

Do you need to run-in a brand new car engine for current cars?

  • Yes - it should be driven at low-revs until 1000KM

  • No - New cars don't need to be run-in at all, just drive as you normally would

  • No - But there's other reasons to drive a brand new car slowly the first few hundred KM.

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neoprema

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I've bought a new car, and i'm wondering if one still needs to drive it at low revs for the first 1000-2000KM?
Its not turbo-charged.
 
Machining tolerances are good enough these days that you dont have to do the run in anymore. But its a good idea to take it easy for the first 1000k or so.
 
neoprema said:
Mazda CX-5 2.5
Click to expand...

No special break-in is necessary, but a few precautions in the first 1,000 km (600 miles) may add to the performance, economy, and life of your Mazda.

• Do not race the engine.

• Do not maintain one constant speed, either slow or fast, for a long period of time.

• Do not drive constantly at full-throttle or high engine rpm for extended periods of time.

• Avoid unnecessary hard stops.

• Avoid full-throttle starts.

• Do not tow a trailer.
Click to expand...

Mazda CX-5 Owners Manual - Break-In Period - Driving Tips

www.mcx5.org www.mcx5.org
 
I've seen some journalists recommend giving the motor a mixed load but don't baby the engine or it will not have as much flexibility in the long run. My mate and I used to both have the exact same fiesta, he babied his from the beginning and I just drove mine normally, like I stole it sometimes, I remember getting in his to drop him off at the airport and it felt pap in comparison to mine.... Almost didn't wanna rev past 4k - however that could have been a lot of different things...
 
ChrisThomas said:
I've seen some journalists recommend giving the motor a mixed load but don't baby the engine or it will not have as much flexibility in the long run. My mate and I used to both have the exact same fiesta, he babied his from the beginning and I just drove mine normally, like I stole it sometimes, I remember getting in his to drop him off at the airport and it felt pap in comparison to mine.... Almost didn't wanna rev past 4k - however that could have been a lot of different things...
Click to expand...

I'd rather follow the manufacturers recommendation (the people that built the engine), than follow your Brakpan approach.
 
Mototune it or gtfo.



What's The Best Way To Break-In A New Engine ??
The Short Answer: Run it Hard !

Break In Secrets--How To Break In New Motorcycle and Car Engines For More Power

New Engine Break In Procedure For Cars, Motorcycles, Motocross, Snowmobiles and Boats
www.mototuneusa.com
Why ??
Click to expand...
Nowadays, the piston ring seal is really what the break in process is all about. Contrary to popular belief, piston rings don't seal the combustion pressure by spring tension. Ring tension is necessary only to "scrape" the oil to prevent it from entering the combustion chamber.

If you think about it, the ring exerts maybe 5-10 lbs of spring tension against the cylinder wall ...
How can such a small amount of spring tension seal against thousands of
PSI (Pounds Per Square Inch) of combustion pressure ??
Of course it can't.

How Do Rings Seal Against Tremendous Combustion Pressure ??

From the actual gas pressure itself !! It passes over the top of the ring, and gets behind it to force it outward against the cylinder wall. The problem is that new rings are far from perfect and they must be worn in quite a bit in order to completely seal all the way around the bore. If the gas pressure is strong enough during the engine's first miles of operation (open that throttle !!!), then the entire ring will wear into
the cylinder surface, to seal the combustion pressure as well as possible.


The Problem With "Easy Break In" ...
The honed crosshatch pattern in the cylinder bore acts like a file to allow the rings to wear. The rings quickly wear down the "peaks" of this roughness, regardless of how hard the engine is run.

There's a very small window of opportunity to get the rings to seal really well ... the first 20 miles !!

If the rings aren't forced against the walls soon enough, they'll use up the roughness before they fully seat. Once that happens there is no solution but to re hone the cylinders, install new rings and start over again.

Fortunately, most new sportbike owners can't resist the urge to "open it up" once or twice,
which is why more engines don't have this problem !!

An additional factor that you may not have realized, is that the person at the dealership who set up your bike probably blasted your brand new bike pretty hard on the "test run". So, without realizing it, that adrenaline crazed set - up mechanic actually did you a huge favor !!
Click to expand...

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