oil pump pressure

[Woody1]

question for all of you. When I start-up my oil pressure guage is fine. Has plenty of pressure. After she gets warmed up, at idle guage reads a low pressure, when engine revs, pressure goes up also. Isnt the pressure supposed to remain constant? I have spoken to the service advisor at dealership, he says its ok, but we all know how these "advisors" can be! Help this boy out! Gimmie a reason why this does this, and if it is ok, why.

[BDBWTE]

Your oil pump runs directly off your internal rotating assembly of the motor.  Thus the faster or more rpms the motor turns the higher the oil pressure is going to be.  At cool startups you motor runs with more r's to obtain operating temperature.  At idle all you need is about 15-20.  As your motor rev's the oil pressure sequentially goes up.  As long as your motor is turning and their is oil in the oil pan over the pickup then the pump is working properly.  I have never seen an oil pump on a small block chevy go out.  The pump is simple two gears.  Your truck is fine, don't sweat it.

[Guest Friz]

That's perfectly normal. the oil pump is driven off of the cam. More rpm's, pump spins faster, more pressure. When the motor is cold, the oil is a lot thicker, therefore, more pressure at startup until the oil itself warms up and thins out a little.

Once everything is all nice and warm, pressure goes down. These newer FI motors do tend to run a slightly lower hot oil pressure, IMO. The basic rule is that you need 10 psi of oil pressure for every 1000 rpm.

Hope this helps.