OIL PSI / BRAND / WEIGHT

[YukonLover]

Wait a minute.. So then what is it calibrated to? Even if the dummy gauge as i call them are not entirely accurate.. which i never truly believe they are, it’s still got to be reading in psi…. Even if it is not a precise reading..

Right ?

It reads like I solve calculus... and I can't do that. lol

 

[strutaeng]

Wait a minute.. So then what is it calibrated to? Even if the dummy gauge as i call them are not entirely accurate.. which i never truly believe they are, it’s still got to be reading in psi…. Even if it is not a precise reading..

Right ?

Umm. IDK if anyone has actually done a direct comparison of cluster gauge vs mechanical guage. Maybe with a tee/plumbing and both sender a mechanical guage hooked up at the same time?

To me it's more like "low, medium, and high" readings. I believe Fords of this generation show this on the cluster. I think most cars don't even show an oil pressure gauge, no?

 

[PPV_2018]

Umm. IDK if anyone has actually done a direct comparison of cluster gauge vs mechanical guage. Maybe with a tee/plumbing and both sender a mechanical guage hooked up at the same time?

To me it's more like "low, medium, and high" readings. I believe Fords of this generation show this on the cluster. I think most cars don't even show an oil pressure gauge, no?

Well that’s actually kind of the way i look at it but instead of low/normal/high more like “here’s a ballpark range of the pressure”

Again i never believe the dummy gauges are particularly accurate, but still feel like some sort of system/sensor is measuring psi and pushing the needle around more or less psi.

I am not saying you are wrong, you could be totally correct but also with your theory I think like there would be less inconsistencies in the readings if it was basically reading at low/normal/high. Ie: the gauges would basically only read at 20/40/60 psi (save 0 and 80 psi for equipment failures). But if your gauge is reading 30-35 psi in the city, then 40 on highway, then 25 idling at a red light , just seems like these readings (even if not particularly accurate) are coming from something giving more precise readings than just low/med/high.. but honestly i really don’t know, so. . . Just saying for the sake of discussion.

As far as other vehicles, i really have no idea. Practically every vehicle I’ve ever owned or driven has been a large Chevrolet or Ford SUV or pickup truck with a V8 that definitely *did* have an oil pressure gauge, and the few exceptions I don’t particularly remember. I don’t doubt that most passenger sedans and coupes/crossovers may not even have an OP dummy gauge on the dash, especially newer vehicles.

 

[Donal]

Hi everyone,

I know oil pressure seems like a common question. But, what I don't understand is the constant variations; especially when there is void of any precursor. I have a 2003 4x4 with a 5.3. I replaced the pump, timing equipment, and pick up tube, gaskets ect. And it ran 35-40 PSI cold or hot idle, and around 45-55 under load. This truck had around 224k.

I have another 2001 2 wheel drive, and when I got it, it idled around 30 PSI cold, and 25-30 hot, and under load 39 PSI. I have been delivering for a company packages 3x a week for several weeks, the truck has been running 8-12 hour days, 80 miles a day and idling with limited start and stops. The oil, when cooled and dropped to the pan is a bit tacky, but not dirty. I maybe burned off at most half a quart since I changed the oil about 1500-1800 miles ago. Just last night my oil PSI seemed to be warm fighting 20-25 PSI sometimes not going past 20-22 PSI, and under load various pressures between 32-39 PSI approximately. Noticing a drop here.

I am getting ready to change the oil, and I did some research and shows that Royal Purple HPS has the most zinc at 1275, most oils are more more than 950. Apparently RP is not API standard, so they can add whatever they want, and their film strength is also superior, as I have seen in several test videos. Im looking for a bit more zinc and some extra film strength to keep it going longer. I was hoping to increase some pressure by having a thicker oil. I was thinking of adding some lucas to my current oil brand. But then I seen the natural lucas thickness, and I said what if I just use that and increased to 5w40 instead of 5w30? I heard a lot of people allege lucas made their bearing tolerances worse, so it improved temporarily, but just made the inevitable happen with just straight weight oil. I ahve been using Valvoline MAXlife high mileage for over a decade, but I feel in this engine maybe its not appropriate.

My plan was to use RP 5w40 and a good quality filter, possible replace the oil sending unit. And then say in 1,000 miles run some marvel mystery through it for another 500 miles, and then do a complete straight RP 5w40 swap until I have to change the pump out. Sound like a good idea?

Maybe you can check the operating oil level when the engine is warm and on level ground. Engine at normal idle speed.

 

[Joseph Garcia]

Interesting. As part of an ongoing major mod, I just had my oil pressure measured with a mechanical oil pressure gauge to test the accuracy of my cluster oil pressure gauge, and both gauges were within a few PSI of each other, both at idle and and at 2500 RPM.

 

[strutaeng]

Interesting. As part of an ongoing major mod, I just had my oil pressure measured with a mechanical oil pressure gauge to test the accuracy of my cluster oil pressure gauge, and both gauges were within a few PSI of each other, both at idle and and at 2500 RPM.

That's good to know. Maybe I'm completely wrong and just don't know it then? This is on a GMT900, right? I believe in those vehicles the oil pressure is actually shown on a PID, no? Maybe something changed?

The GMT800s don't show oil pressure on PID, as far as I know.

Thanks for sharing your findings.

 

[Joseph Garcia]

That's good to know. Maybe I'm completely wrong and just don't know it then? This is on a GMT900, right? I believe in those vehicles the oil pressure is actually shown on a PID, no? Maybe something changed?

The GMT800s don't show oil pressure on PID, as far as I know.

Thanks for sharing your findings.

Yes, it is a GMT900 truck.

 

[rockola1971]

Umm. IDK if anyone has actually done a direct comparison of cluster gauge vs mechanical guage. Maybe with a tee/plumbing and both sender a mechanical guage hooked up at the same time?

To me it's more like "low, medium, and high" readings. I believe Fords of this generation show this on the cluster. I think most cars don't even show an oil pressure gauge, no?

Why do believe the mechanical gauge is "more or less" accurate than the sender type? They both have a percentage of error. Doubt GM lists the accuracy range. I would hazard to guess that its a +10/-10% error range which is only +/- 3psi at 30 PSI. While not truly significant error at just 3psi range, it is still an error. The problem with the sender type is the error stacking. You have the sender, wiring connection, Cluster wiring, board connections and traces with the silver migration problems and then ultimately the DC stepper motor for the gauge needle itself. All of those can add to the overall error. Sure the whole system is accurate enough when the vehicle rolls off the line with that new car smell but thing degrade over time and our generation chassis aint getting any younger. Take for instance a wore out front suspension which creates havoc alone on the electrical system with all the jolts every time a decent rough spot in the road or offroad is encountered.

 

[nonickatall]

At first, my truck's oil pressure was relatively low.

I started by replacing the O-ring on the oil pump. That helped a little.

But what helped the most was that for the last four oil changes I have added 1 liter of diesel to the oil before each oil change and driven 20 to 30 km with it.

That loosens the carbon in the engine. I don't know why that increased the oil pressure. According to my technical understanding, it should actually reduce it, because the back pressure in the system is reduced. Maybe it loosened the carbon from the pressure relief valve.

I have no idea.

But my oil pressure is much better. And the ticking noise of my hydross is almost gone.

Of course it is lower when the car is in idle, than when it is driving, and of course it is lower when the oil is very hot, than when it is cold.

But it is never too low since.

 

[Marky Dissod]

Why do you believe the mechanical gauge is "more or less" accurate than the sender type?
They both have a percentage of error. Doubt GM lists the accuracy range.
I would hazard to guess that its a +10/-10% error range which is only +/- 3psi at 30 PSI.
While not truly significant error at just 3psi range, it is still an error. The problem with the sender type is the error stacking.
You have the sender, wiring connection, cluster wiring, board connections and traces with the silver migration problems,
and then ultimately the DC stepper motor for the gauge needle itself.

All of those can add to the overall error.
Sure the whole system is accurate enough when the vehicle rolls off the line with that new car smell,
but things degrade over time and our generation chassis ain't getting any younger.

... my '02 Tahoe now idles at operating temp @ 360RpM ...
... at least according to my tachometer's needle, which has clearly escaped its original tolerances.

I know my engine ACTUALLY idles at 600RpM, because I checked.