1996 5.7 Oil Pressure

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Kayparker96

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So my 1996 with 198k sounds and runs great, but it seems like the oil pressure isn’t correct. At first start up, the pressure seems to be fine. Runs at 40, goes higher when I am using the gas. But slowly lose oil pressure I had almost none(fluttering around 20psi) around an hour / hour an half running.

Could this be the oil pump or the sensor? I’m running 5w30 Redline oil in it.
 

exp500

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Do you live in the frozen north? If not increase oil viscosity up to 15-45. Diesel engine oil works good in these trucks. Especially higher mileage ones like yours.
Next would be verify oil pressure with screw in guage and replace Oil pressure sender.
 

Hoesgottaeat2

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Is that 20psi you're mentioning at idle? In my experience, 40-60psi cold at idle and 20-30psi when hot at idle is normal for the last (4) Vortec 5.7s I have owned.
 

Eman85

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Only one way to know, pull the sending unit and put a mechanical gauge on to test. I've got 3 trucks with Vortecs mileage from 130k to 190k all run 20 psi hot at idle and 40 psi hot going down the road. All run 5w-30 Mobil oil. The 97 fluctuates at idle on the gauge but it's in the gauge itself as I checked it with a mechanical gauge. Factory gauges are more of an indicator than an actual accurate gauge plus the accuracy diminishes over time from wear and tear and corrosion.
 

Hoesgottaeat2

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I agree with @Eman85. I'm more of a 10w30 guy with the higher mileage but that shouldn't matter much imo. Mechanical gauge never hurts. Unless of course the tubing leaks in the cab somewhere lol. On my older, much older cars I use electric aftermarket gauges as opposed to mechanical for just that reason.
 

OR VietVet

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So my 1996 with 198k sounds and runs great, but it seems like the oil pressure isn’t correct. At first start up, the pressure seems to be fine. Runs at 40, goes higher when I am using the gas. But slowly lose oil pressure I had almost none(fluttering around 20psi) around an hour / hour an half running.

Could this be the oil pump or the sensor? I’m running 5w30 Redline oil in it.
Welcome to the forum.

You did not say. Is this a new development and if so, what did it show before? Sounds normal. Use a mechanical gauge to check.
 
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