ST oil pressure concern/question

2004Droptop

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I think my oil pressure runs low... so I am running Motocraft 5W30 synthetic blend with a Motorcraft filter. Assuming the gauge numbers are right it runs about 52-70psi cold under load depending on temperature, at hwy speed (at temperature being close to 200) seems to be about 18-20psi first mark, at idle about 9 psi (at temp). I added a pic so you can see where on the gauge I am talking about.

I am curious of what pressures you guys are seeing?
IMG_0314oilpress_zps675ca074.jpg
 

FISHTAIL

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Nah. I checked mine again this morning and that's almost exactly where mine sits as well. Looks pretty normal to me.
 

FORDSVTPARTS

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Those gauges are barely any better than an idiot light, they're really only there to look neat.

If you want to know what your oil pressure is you need a live gauge.

Years ago a lot of people were coming in because of low oil pressure readings in Aerostar vans, there was nothing wrong with the van, the fix was replacing the gauge with a recalibrated gauge and the engines were never touched as they were fine.

-Steve
 

RedRocketMike

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Negative, about 9-10psi at idle is correct for this car. My Jeep only ran about 9psi of pressure at idle too. It's not unusual.


I would be really disappointed in that pressure at idle. That's probably barely over what it takes to float the crank. I wonder what it will be after 150,000 miles of wear.
 

FISHTAIL

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So you've checked the STs oil pressure with a live gauge? Just curious.

No, just going off of the gauge mounted up top. Whether or not it's accurate doesn't really apply here...he was worried that his was reading low. At least compared to mine, and other posts I've seen over on FocusST.org, it's not. That reading is normal.

Now...if it's actually only 9-10psi is a different matter entirely. Won't know that unless I hooked up another gauge to the system to check it. I don't know why Ford would bother putting an inaccurate gauge up there, at least if it was erroring on the low side. You'd think if it was that bad they'd have had it scew the other direction so as not to worry folks. I would be interested to see what kind of reading a mechanical gauge shows alongside the factory one though...just to see how right or wrong it actually is.
 

FORDSVTPARTS

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What I was getting at is that without actually checking true pressure it's all guess work because no one knows how the gauge is actually calibrated.

I guess I'd say if the gauge shows pressure you're fine.

It would be interesting to find out what the actual pressure is, just a matter of time before someone installs gauges and at that point we'll all know.
 

Jimmysidecarr

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You technically only need between 6 and 8 PSI of oil pressure per 1,000 rpm.
That is to be checked when the oil is as hot as it is likely ever to get.

All oils thin when they get hot and thicken when they cool off, therefore a car's hot oil pressure will always be lower than it's cold oil pressure.

The oil pressure is also RPM dependent, for the most part.

Thicker oil and overly high oil pressure does not equal better protection. Chemistry is where the most significant protection gains can be made, because the oil's film strength can greatly benefit from superior chemical compounds being used in certain oils.

Film strength matters because there are lots of lubricated areas that are not pressurized journals.

Above a certain RPM the pressure does not need to increase any more because of the hydrodynamic wedge created by the rotation of the parts being lubricated by a pressurized journal. The hydrodynamic wedge creates the cushion, the oil simply needs to get delivered.

Most engine oil pumps have a pressure relief valve that allows the pressure to plateau at a certain predetermined high. More pressure is not needed at very high rpm.
 

jonb347

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Those gauges are barely any better than an idiot light, they're really only there to look neat.

If you want to know what your oil pressure is you need a live gauge.

Years ago a lot of people were coming in because of low oil pressure readings in Aerostar vans, there was nothing wrong with the van, the fix was replacing the gauge with a recalibrated gauge and the engines were never touched as they were fine.

-Steve

actually they aren't idiot lights on anymore. if you look in the shop manual you will see they are live electric gauges. and that is within spec. mines the same way as well.
 

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