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Q: Oil pressure

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Hi just wondering if there should be oil pressure while car is not running? Because when I turn the ignition on the pressure is reading at quarter? When I start the car it moves up to 3/4 at idle and when warm and driving it sits just below the top mark but drops back down to 3/4 at idle or just cruising? Cheers Nathan

My car has 375000 miles.
My car has an automatic transmission.

A: There are aftermarket oil pre-charge system...

There are aftermarket oil pre-charge systems that pressurize the lubrication system the instant you turn the key to the "on" position. But, unless you have such a system installed in your car, oil pressure at key-on should be "zero". If the gauge reads positive pressure when the car is off, there is something wrong with the gauge. You could have the gauge evaluated and replaced if defective.

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