Which risk increases when a cold engine is rapidly accelerated before oil reaches optimal operating viscosity?

💡 Explanation

When a cold engine is rapidly accelerated, the oil viscosity is high and doesn't properly lubricate, causing boundary lubrication where direct contact wears the crankshaft bearings because the oil film is insufficient. Therefore, crankshaft bearing wear is initiated, rather than other failures linked to temperature or mixtures.

• Which risk is increased when reinforced concrete rebar experiences hydrogen embrittlement following exposure to acid rain?
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