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Because all engine parts expand with heat which increases the oil clearances. If it is an higher mileage motor add a can of STP with every oil change; that will help. Oil thins when it is heated. Thick oil takes more to push through the engine than thin oil. Your Main Bearings are shot. I wouldn't go so far as to say the bearings are shot. Depends on how much oil pressure drop we are talking about here. Droping to zero means there is a problem. But if it drops to 20 - 30psi then that is normal.

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โˆ™ 2008-05-08 21:40:37
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Q: Why would you lose oil pressure in a V8 motor after it warms up?
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