When an engine is correctly rebuilt or reringed, (rings only dosed with light oil not slathered in greasy oil), correctly clocked (open ends never on thrust or piston pin areas)
The engine is started and allowed to full warm up while mech checks for leaks and tests oil pressure, and keep revs at 1000 or 1500 for a small engine. The engine should operate in perfect tune, not loose tappets or direct fan or other lunacy.
Once its warm, the mechanic then should drive the car in gradual load steps of.
Accelerating gently to mid range torque in 2nd gear and letting it overrun down back to idle abt 3 or 4 times.
Accelerating briskly on open road in 2nd gear to 60% safe engine speed and letting it overrun back to creep about 5 times,
Accelerating in burst from roll of 2nd gear to abt 80% engine rpm and letting it overrun back to creep.
This act seats the rings nicely against the bore as the cross hatch from cyls gets pushed down and ring surface loses its rough edge.
Oil helper rings prevent oil drainaway and can flood the 2nd compression ring causing the cylinder walls to "polish" meaning burnt caramalized oil gets deposited on the cyl and also the ring stack which is terrible.
Once the initial steps are complete just drive normally.
