Oil pressure

[Alfredo7474]

Just changed my oil pressure sensor on my 1990 gmc k1500 5.7. It stays at about 30-35psi while driving even at high speeds, it goes down to about 25psi when at a red light and goes back up to 30-35 when I give it gas. Is that normal psi for these types of trucks? Thanks

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[Komet]

I like to see 10psi per 1000rpm but I wouldn't say your engine is having a problem.

 

[tpass]

The only way to be sure what your actual pressure is, is to have a mechanical gauge. The dash may could be incorrect as well.

You could put a "tee" on the sending unit and cross check it.

 

[Scooterwrench]

A 90 with 25 pounds of oil pressure? You lucky dog!!!

 

[fancyTBI]

Yes it’s fine. Mine has ‘92 has 45-50 going down the road and 25 at idle. Motor has 160K on it.

 

[Schurkey]

I'd say that's good--even exceptional--at idle, but nothin' special at highway speed. What oil viscosity are you using?

My '88 K1500 5.7L will almost peg the gauge (60 psi gauge) when revved-up, at steady highway speed I get about 45 psi. But only ~15 at idle. Using 5W-30 Amsoil XL.

Does your sending unit match the gauge? (i.e., 0--60 psi sending unit for a 60 psi gauge, 0--80 psi sending unit for an 80 psi gauge)

 

[Alfredo7474]

I'd say that's good--even exceptional--at idle, but nothin' special at highway speed. What oil viscosity are you using?

My '88 K1500 5.7L will almost peg the gauge (60 psi gauge) when revved-up, at steady highway speed I get about 45 psi. But only ~15 at idle. Using 5W-30 Amsoil XL.

Does your sending unit match the gauge? (i.e., 0--60 psi sending unit for a 60 psi gauge, 0--80 psi sending unit for an 80 psi gauge)

I’m using Quaker state 5w-30. The sending unit should be for 60psi. I don’t know if I need to tighten the sensor more because when I rev the truck goes up to 45 psi. But when I’m driving it stays at about 30-35 psi no matter the speed. But I’ve heard these gauges aren’t always accurate.

 

[Komet]

Only tighten the sensor if it's leaking oil; the sensor output is not affected by its position or tightness.

 

[Scooterwrench]

I see your ol truck has almost 315,000 miles on it. Next oil change you may want to put a little heavier oil in it. Go to a 10w-40. As mileage goes up and engine wear has increased it's good to run heavier oil. Eventually it will get like mine where pouring 90 weight gear oil in the pan won't give it any oil pressure.