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I just changed my engine's piston rings and do not know how long I should let the engine break in. The engine is an '06 Chevrolet 1.5L SOHC. And how is the procedure done just by letting it sit idly?

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Piston ring breaking standard procedure involves how the engine is used for the first 500 miles.

  • No extended idle time
  • Easy low power driving with lots of changes of rpm
  • No high power accelleration or high load.
  • No steady speed driving as in long trips with steady cruise speed

Some oil burn is not uncommon in the first few thousand miles. An oil change at the 500 mile mark is a good idea.

  • Don't use synthetic oil for break in. Conventional "dinosaur" oil. I prefer Shell Rotella 10W-40, which is fairly cheap, has high surfactants and detergents for diesels but works well as a "break in" oil. Change at 500 miles to your regular oil like Fred suggests. Just don't pour Comet or BonAmi cleaning powder into your carburetor, even if you had one.... – SteveRacer Jun 11 '16 at 11:09
  • @SteveRacer In our shop choice of oil depends on cylinder surface finish. Conventionally honed cylinders get 30 wt conventional oil. Modern "plateau" honed cylinders get conventional oil of the standard weight for that engine and old flat tappet engines would get a break in oil with ZDDP additive. I have not used 10w40 in 20 years. Added abrasives would be counterproductive. – Fred Wilson Jun 11 '16 at 15:40
  • Agreed. No idea how/if OP honed; doubt it was a Sunnen. I feel chrome alloy rings take forever to seat on synth. For a BMW, I can't deal with Nikasil, even for a new crosshatch. I leave that to folks with much better equipment, and follow their break-in oil recommendation. My '72 2002tii M10 gets rebuilt quite often, but no NIkasil and rocker arms -- so I use Rotella. Not a problem on newer engines, other than a possible delay in ring seating. There were a lot of failures in the '05-'06 seasons of my vintage racing series, when zinc/phosphorus dropped to .08% -- tribology=alchemy to me. – SteveRacer Jun 12 '16 at 1:45
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I'll stick my neck out and fly against convention. There's a great article here:

http://www.mototuneusa.com/break_in_secrets.htm

I've verified this method with a number of motorcycle and race engine tuners who all agree and it pretty much sums up what they do.

Tldr; warm up the engine gently, then give it a very thorough workout!

The main point is that you need the combustion pressure to push the piston rings to sit into the bore perfectly, then you get excellent, even compression, minimal blow by and a good engine.

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This is similar to RemarkLima's answer. Figured I'd list the steps I follow.

Start the engine.
As it is heating up, rev it through the entire rev range a couple times.
Keep an eye on coolant, temperature, oil pressure.
set timing
Go out for a drive. Get it into top gear and go WOT a bit. Do this about 5 times for couple seconds each.
Go home and change the oil.
Afterwards, take it easy on the engine for the next 1000 miles. no WOT.

As was mentioned in Fred's answer, always use non-synthetic oil for the break-in.

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