# [SOLVED] Oil pressure



## Basementgeek

OK gear heads I have a question on oil pressure.

I have 5.3L V8 in a 1999 Chevy Z71 Pick up, 131,000+ miles, automatic. Oil was changed about 2,000 miles ago, 5W30, I have been told.

Well last weekend I put about 300 miles on it and about 2,000 RPM the dash gauge (oil) would indicate 40 PSI, today it was down to about 20-25 PSI.
Today idle is only about 10 PSI ( The engine is hot).

Yes, I know I need to put a direct reading gauge on it, but don't have one anymore. I will have one hook up after I get the oil changed. Since I bought the truck used a few months ago, I can't swear when it was last changed, but oil looks "clean"

Question is what do do you think the Oil pressure should be at idle and 2,000RPM, when hot.

I have no bottom end noise or valve noise, runs good, but my son said it died on him the parking lot today. No check engine light. Never has died on me.

BG


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## wolfen1086

*Re: Oil pressure*

Any weird noises? 
Whines?
did they or you use a Fram oil filter? (please say no even if your lying to me LOL)
Has it always had 5w30 in it?

there could possibly be a sludge buildup on the screen I have seen that once or twice in my life, or at 131k something could be about to finish wearing out.
On the other hand I had a 76 350 ( 5.7L) with 175k on it and it ran 12-20 warm, and that old lady lasted years.

Oh and when did the pressure start dropping?


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## Basementgeek

*Re: Oil pressure*

No strange sounds at all.

Most likely a NAPA filter, the shop I bought the truck is big on NAPA parts.

I have no clue what oil has been used, I've only owned about 11 months. Book calls 5w30

I did start it later on when the enginge was cold, 20 lbs idle 40 lbs at 2,000 RPM.
I will get it changed in the next day or two and see how it goes.

I put a few miles on it the other day and did not notice anything. My som borrowed to today and he told me.

BG


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## octaneman

*Re: Oil pressure*

BG 

Ive seen this before; mechanically nothing is wrong with engine, the computer has a glitch in its software code on the oil light, and a few other sensors , it needs to be re-flashed with the updated patch for your engine. 

All engines.
4.8L, 5.3L , 6.0L V8 Engine VIN V, T, U , RPO, LR4, LM7, LQ4


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## Basementgeek

*Re: Oil pressure*

No oil pressure light, it has a gauge. How ever there is information panel that may had a message while my son was driving it.

Is there a low oil pressure cut off switch to kill the engine if the pressure drops to low?

Thanks

BG


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## Midnight Tech

*Re: Oil pressure*

Usually the same sender that does the light on late models also has the engine cut switch in it as well.


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## Basementgeek

*Re: Oil pressure*

Getting the oil changed, in a couple of days and my mechanic is also going to check with a mechanical gauge. Going to have 10W40 put in it.

5.3L normal pressure, book says, at 2000 RPMs is 20PSI. That seems low but he said Chevy are low compared to engine makers. Running down the road today, engine hot, at 2000 rpm gauge said about 20 psi.

Thanks

BG


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## Wrench97

*Re: Oil pressure*

5w30 does give you better fuel millage over 10w40, I doubt you'll see a lot of difference in the gauge readings with it, the biggest 5 things I've seen is fuel in the oil which you'll be able to smell and temperature make a difference in oil pressure readings.


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## Basementgeek

*Re: Oil pressure*

Thanks.

There is no gas in the oil as far as I know. Truck runs about 200º when up to operating temp.

Not really concerned about fuel mileage, when you only get about 12mpg in city, so it could go down to 11½. Most weeks it may see only 50 miles total.

BG


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## Wrench97

*Re: Oil pressure*

I had a 88 F150 that I ran 15w40 in didn't need to add between oil changes. didn't leave puddles on the ground, at 175,000 I started to drive farther to work my buddy talked me into using synthetic 5w30, lower oil pressure, left puddles everywhere darn near burnt it up @2000 miles on the oil change it needed 4 qts, went back to 15w40, sold it @ 255,000

If there was gas in the oil you would smell it on the dipstick.


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## Basementgeek

*Re: Oil pressure*

No smell on the dip stick, wiped of with a paper towel, burned just like oil would.

I have zero use for synthetic oil, tried it once and just all kinds of valve noise. I changed within a couple hundred of miles.

BG


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## Wrench97

*Re: Oil pressure*

It's are new Green program at work, we're using 10w30 synthetic in the trucks, about 50% are converted fuel millage is up .3 for the fleet.


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## wolfen1086

*Re: Oil pressure*



Basementgeek said:


> No smell on the dip stick, wiped of with a paper towel, burned just like oil would.
> 
> I have zero use for synthetic oil, tried it once and just all kinds of valve noise. I changed within a couple hundred of miles.
> 
> BG


I'm glad theres no smell on the dip stick, thats always a good sign, especially with over 100k on a engine.


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## Basementgeek

*Re: Oil pressure*

Taking it in Thursday, and put a direct reading gauge on it. Then change the oil and filter. Sticking with 10W40 in it. 

BG


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## wolfen1086

*Re: Oil pressure*

If the direct reading gage shows different oil pressure have the sending unit changer first, if the pressure is still low either bend the needle or change the gage.
But after 100,000 miles I usually recommend people to use 10W40 in the summer and 
10W30 in the winter, unless the 10w30 causes a pressure drop, then I recommend rebuilding or replacing the engine. In some case you can get away with just an oil pump swap, but if ya still have low oil pressure after that its the cam bearings that are going out


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## shawnpb

*Re: Oil pressure*

Clean out the oil pan. Could have too much sludge build up. Reset with new oil pan seal also new oil pump.

Also try lucas oil treatment. One of the benefits are "Raises oil pressure.


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## Basementgeek

*Re: Oil pressure*

I don't think there will any sludge in it, looks like it was well taken car of. Again the book says 20 PSI @2000 RPM.

BG


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## shawnpb

*Re: Oil pressure*



Basementgeek said:


> I don't think there will any sludge in it, looks like it was well taken car of. Again the book says 20 PSI @2000 RPM.
> 
> BG



Doesn't oil create sludge & metal shavings over time mostly with automobiles with 100 thousand+ miles?


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## Wrench97

*Re: Oil pressure*

Good oil will have additives to clean the sludge out providing it's changed on the recommended schedule.


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## Basementgeek

*Re: Oil pressure*

If you change your oil regularly you should not have a problem with sludge. The only time I have seen it be a problem is if someone never changed it. Needs to be changed some place between 3,000-5,000 miles, some times even 7,000 miles is all that is required.

Oil has gone a long way in the last 30-40 years. Oils of years ago were non-detergent and they did not clean like the detergent oils of today.

BG


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## bruiser

*Re: Oil pressure*

There is an oil, lube, and additive forum, probably more than one, that has lots of info. The one I'm speaking of is bobistheoilguy. People actually use oil analysis to find the best oils for particular engines. The oil that has been testing best for GM V8s is the Castrol Syntec 0W30, made in Germany. You have to read the back of the container for the Made in Germany info. One of the Pennzoil synthetics has also been testing really well for GM V8s. I don't remember which one.


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## Basementgeek

*Re: Oil pressure*

The synthetic oils are out of the question. This engine has 130,000 miles out it. Tried them before and the engine (valves) were noisy. I know there newer cars out there that require it..

BG


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## Basementgeek

*Re: Oil pressure*

Got nothing done on it. No adapter for direct oil pressure gauge that big.
( unless NAPA sent the wrong part, very hard to get to also).

Mechanic said the oil doesn't need changed because of how clean it is, less than 3000 miles since the last change.

Oh well, I will just keep an eye on the guage.

Thanks

BG


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## wolfen1086

Keep an eye on the gage man, mentally or on paper remember the pressure bot warm and cold in various weather conditions, if say its 80 deg one day and you have [email protected], and the next day its 80 deg and you only have [email protected], then you either have something mechanical going bad or a funky gage. But historically I have always been told my whole life that with most GM's as long as you have oil pressure going to the top end your pretty mush ok, pull the oil fill and look inside with a flashlight while its running and see if theres oil running down the rockers and push rods, if there is your ok if theres isn't your in a bad way.


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## SABL

Just from personal observation........

I carry better oil pressure with the 5W-30W. After trying different weights of oil in all seasons I found that 10W-30W (or even 10W-40W in the summer) did not carry the same pressure as the 5W-30W. After many years of careful watching I always use the 5W-30W.......year 'round. With 247K miles, you better believe I keep an eye on ALL guages!! 

Oil and filter are from NAPA.....I only use the gold series filters. 

Don't wanna discuss Lucas or any type of oil additives.......have no use for them....even at my high mileage. Engine does not smoke and sounds very healthy.....no noise from lifters or any moving components. 

If an engine calls for the lighter weight oil, use it and do not deviate or put in additives.


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## wolfen1086

I'm with SABL, the onluy thing I have ever put in my crank case other than oil is risalone, and that was on a old Chevy truck I paid $500 for that had a MAJOR sludge build up that the risalone cleaned out.
But heres MY take on additives

Slick 50, don't need oil with this stuff? then why do they make oil
Lucas, yea teh injector cleaner, but why thin the oil out ?
Duralube, space shuttle huh? Yea theres a reason they only used it in space for so many years


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