Heat is the enemy to new engines... that's why the manual says no prolonged operation above 7000pm to start. Rev the engine freely but avoid anything that will cause excessive heat... i.e. lugging the engine
truck part with low rpms, traffic jams, constant high speed riding and long highway droning. Excessive
heat on a new engine causes parts to glaze instead of mate.... Revving the engine to redline here and there while breaking in the engine will actually speed up the break in and help mate parts quickly. Babying the engine too much during break-in is just as bad as excessive heat.... parts will glaze, not mate.