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?
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.
I'll stick my neck out and fly against convention. There's a great article here:
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.
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.
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.