Let's face it, modern computer controlled equipment works to far closer tolerances and at higher honing speeds, lasers quality and accuracy check all parts automatically, so the engine of a modern, cheap mass produced car needs little of the care that 60's and 70's engines needed. Bores and crank/con rod bearings in those days, could easily hot spot if worked hard before the roughness of the machining had been honed smooth by the normal movement of the parts, and allowing the oil to permeate the microporous surfaces. Working a tight, new engine too hard would overheat the high spots, causing localised melting, heat distortion and partial (and occasionally complete) seizure of the engine.
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