Oil Pressure

[tbmmbt]

This may not be the right place for this question but here goes. I have noticed on my 4.3 liter Chevy motor that when the engine has been run and everything gets completely heated up then when I come to a stop and put it in park that my oil pressure gauge goes down to 20 lbs but when I go back into drive and push on the gas it jumps up to 45 lbs or so. I really didn't think that it went down that far (thought a shy 40 before) Is this low a pressure in park (some 20 lbs lower) OK or is there something that needs to be done? When I first start it up the pressure would go up to 60-65 lbs and gradually work its way down to 45 lbs at normal operating temps. Didn't know if there was something bad I could stop from happening to the motor. Any help if needed is appreciated.

Butch

 

[ekpolk]

That does not sound like a big deal to me at all, especially with the oil hot. My wife's Sequoia had an O/P guage, although it's not numerically labeled, it has tick marks almost identical to those of the fuel guage. With that as a comparison, we routinely see the 1/4 indication at hot idle, and sometimes more than 3/4 when winding it up some. That said, I'm not en expert on the 4.3L engine by any stretch, so if some Chevy/GM guys have better scoop, I'd certainly listen to what they have to say.

 

[fantastic-damage]

I have a Chevy Blazer with the 4.3L and my oil pressure does the same thing. Don't worry.

 

[tbmmbt]

Well I didn't know if that was good or not. It used to be a little lower than the 40 lb mark at idle but now 20 lbs. I haven't owned it but 5 weeks so just trying to stave off trouble if needed. When I bought it I changed the oil to 5w30 Havoline and have put about 1500 miles on the oil so I am going to change it again now after the first 1500 that I have put on it to see if any cleaning has been done. Probably not but at $10 for an oil change it won't hurt. Thanks for replying.

Butch

 

[427Z06]

Your oil pressure sounds about normal. The previous owner may have used something like a 15w40 HDEO or High Mileage 10w40 oil, and thus the higher readings. Unfortunately most people think these higher than spec readings are better, but in fact, once you reach the oil pump bypass pressure, oil flow is reduced which is not better.

 

[TallPaul]

It's perfectly normal for the oil pressure to be lower at idle than at cruising speed. The 60-65 cold is because the oil is a whole lot thicker then. My '95 F150 has hot pressure with 10w30 of about 40 psi at 2000 rpm and 17 psi at idle (cold is around 55 psi). Some vehicles will have a range that is higher like 30 to 60 psi, but nothing wrong with the pressures your getting.

 

[tbmmbt]

Thanks for the replies. I just wanted to be sure all is well with the pressure it was showing.

Butch

 

[porcupine73]

Your pressure conditions sound similar to what I see in my Subaru. The service manual for your vehicle should might have a spec for a minimum oil pressure at idle RPM.