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What is normal for oil pressure? [Expired Topic]

22517 Views 9 Replies 5 Participants Last post by  kknobl
I noticed that my 99 2wd 5.7 with 145k has quite a range for oil pressure....

At times, it seems to ride down in the 20s (the guage shows a range from 0 to 40 in the middle to 80 at the top), and others it's up in the 50s up to 60....

It's running fine, and I've not noticed anything weird except for the wide range of pressure....

Coolant temp seems to ride steady no matter what the oil seems to be doing.

Is that normal?

Thanks - Tim the technojunkie
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I have a 99 4wd 350 that has a little over 111,111 (I just missed it) and my oil pressure varies a lot also. All else seems fine, but it does use a quart of oil in less than 2000 miles. Can someone explain?
Oil pressure varies with air temperature, engine temperature and even engine speed.

When you first start your truck the oil is at it’s thickest, thus highest oil pressure.

When it warms up the oil gets thinner, and pressure gets lower.

As you drive you vary oil pressure because of RPM differences, Higher RPM, higher oil pressure.

Lower RPM’s lower oil pressure, like when idling at a traffic light.

There are times when you may get a unusual drop in pressure that can be caused by a piece of dirt stuck in the sending unit.

Constantly low oil pressure all the time is an indication of low oil level, clogged oil filter, week oil pump.
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Makes sense....

Yeah - that makes sense! Thanks '84!

This is my first vehicle that has something more than "idiot lights", so of course I'm diggin all the new stuff!

I appreciate the input!

Tim the technojunkie
There is a reason they call them idiot lights,

the average person doesn't understand what I just explained so an idiot light just tells them when they are out of oil.

Nothing against anyone but no matter what you drive, a Burb, or a VW if it has an owners manual take the half hour out of your life and read it, cover to cover.

It will explain a lot of things and even give some good advise.

Happy trails.
Owner's manual

That's the one thing that kind of disappointed me when we got this one - There wasn't a manual.... I'm a book kinda guy and need to read!

I found one on Ebay, so that's been rectified...

Kinda weird though - when I sold my 92 Taurus wagon, I gave the buyer the original manuals that came with it, the extra keys, the Haynes manual that I had for it - you know - everything that was specific to that car.

When I bought this truck from a local Chevy dealership - there was no manual, only one key, and no remote for the locks....

Who would get rid of an owner's manual?

Makes me think this may have been repo-ed instead of traded in. I know at the price I got it for, they couldn't have paid a whole lot for it.... (Lucky me!)

I wonder if dealerships maybe just strip these things down when they get them.... Harvest all the little stuff that can be re-sold and just sell the base vehicle? Maybe the clean/refit mechanics just "clean out" the vehicle when they get them?

Before we bought our 99, we looked at a 95 GMC Suburban at a local used lot, and when we took it for a test drive, we looked around and found a bunch of stuff I can't believe anyone would leave in a trade-in.... Motorcyle keys, batteries, binoculars, and a bunch of random papers in the glovebox. Must have been a repo - "pre-cleanup".

Just kinda weird.

Thanks for the insight guys!

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technojunkie said: I noticed that my 99 2wd 5.7 with 145k has quite a range for oil pressure....
Oil pressure will usually be higher when the engine is cold, lower when warm. GM is now using 5W oil in their newer engines, quite a change from the days of 30W and higher. The lighter oil helps to increase gas mileage and today's engines have much closer tolerances than in the "good old days" so thinner oil is need to properly lubricate the friction surfaces. The most important thing about oil pressure is any sudden change...such as going from middle of the guage to zero or all the way to the higher end. That means something is wrong. Gradual moves are pretty much normal. When I was in high school many years ago I had a 1941 Ford with the flathead V-8. Upon cold startup the oil pressure guage would peg at 40 lbs. As the engine warmed up the reading gradually dropped all the way to zero. This was because the main bearings were severely worn. But the engine ran fine.....with a zero reading on the guage. So again, it is not so much the pressure reading, but sudden changes that you want to watch out for.
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Newbie question for my 1993 Burban...

In reading the owners manual, it says that the oil should be warm prior to checking it.

I checked the oil before starting the engine tonight and it was just above the add line. But, when I checked after the oil had warmed up and had a chance to settle again, it was well within the "operating range" area of the dipstick, which I take to mean that there's enough oil in the engine.

Here's my thing: I've always been told to check the oil before you start the engine - before the oil gets warm - so that you get the most accurate reading. So I'm curious as to what the general practice is for checking oil on the 5.7 V8?

I check it before ever starting the engine, first thing in the morning
Thanks for the info.

I topped it off last night, but it looks like I might have overfilled it just a touch - should I be worried? Will it be OK to drive for a day? I have an oil change scheduled for Saturday AM so it will be corrected.

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