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Slowly but Surely
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When I start my car up nowdays, the stock oil pressure guage reads close to 40lbs/in.sq. But after I give it a good drive and pull back into my backyard, I notice the pressure now reads close to 20 lbs/in.sq. Is it normal or is there something wrong. I hate to see the oil pressure needle so low so I was just wondering.

Thanks, Neal
 

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Moderator, megalos ntabatzis!!
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its only supposed to be like 10 psi at idle when its warm and about 50 at 3k... mines like 15psi at idle and just under 50 at 3k... You should be fine...
 

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Oil pressure will drop as the engine warms up. I run 12 to 15 psi at idle with the engine at operating temp. with 20W50 Castrol GTX oil in it. It will run 65 psi when it fires up and 45 psi at 2600 rpm going down the road. These readings are off a mechanical oil psi gauge. I would be skeptical about trusting the stock gauges a whole lot.
 
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Well, if you haven't changed your oil in a while, it'll eventually lose a lot of its viscosity and you'll lose pressure. I lost about 20psi when the oil started to break up in my car. Changed it and it fixed the problem. As long as you're still flowing good, though, there shouldn't be any problems.
 

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Dr Wheelspin Rh.D.
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Yeah that's normal, as oil heats up it becomes less viscous, thus the 10w30 rating - 10 for hot weight, 30 for cold weight. Also the stock oil pressure gauge is very inaccurate, especially after 11+ years. Changing out the oil pressure sending unit would probably show you a more correct value, but it's still a slow reacting and inaccurate gauge.
 

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wastegate hose is pulled
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Bishop92T said:
Yeah that's normal, as oil heats up it becomes less viscous, thus the 10w30 rating - 10 for hot weight, 30 for cold weight.
Multi viscosity oil is specifically formulated to counteract the temperature/weight properties of single weight oil. 10W is the low temp rating. At high temperatures it takes on the properties of a 30 weight. It is still thinner when hot, just not as much as a single or "straight" weight oil. :)

Twenty psi at a hot idle is well within specification.

A drop in oil pressure from previously normal reading indicates internal engine wear. Temperature, the type of oil, how fresh it is and rpm all need to be constant for this to be true though.
 
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