Oil Pressure Range

[Ultramaroon]

Originally Posted by mxm64

Initially yes, started at max scale (over 100) on a 40F day and slowly came down after warm up and then lower yet after a spirited test drive.

It does seem a touch low but as long as you aren't scuffing the rod bearings you should be ok.

Look into used oil analysis (UOA) and see if you're accumulating any unsavory materials.

[mxm64]

That is scary for me even to imagine again. I am going to buy a mechanical test gauge to compare. Not sure I am comfortable switching to 5w30?

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[Ultramaroon]

Backup/reference gauge is an excellent idea in general.

You have an oil pressure gauge and are now becoming familiar with the pressure-to-temperature relationship. As long as you keep in mind that the main and rod bearings are most vulnerable at those pressure extremes, you can safely experiment with different viscosities.

Keep in mind that at those cold-start temps you are getting high pressure because the clearance between cranskshaft and journals is at its minimum and the oil is thicker. Just be gentle with the engine until the pressure drops to the approximate 10 PSI/1000 RPM rule of thumb.

[mxm64]

Tested with a Harbor Freight Mechanical Gauge in oil gallery against the MaxTow Gauge in the factory low oil pressure sensor location. Basically the two agree fairly well except at idle when oil gets hot. MaxTow reads about 1/2 of the mechanical gauge. Makes me feel better at idle but pressures still don't meet factory spec at 5k rpm (couldn't go to 6k while parked because of my launch control tune). Here is the data, but still trying to display it nicely in some graphs:

https://docs.google.com/spreadsheets...it?usp=sharing

Originally Posted by Ultramaroon

Backup/reference gauge is an excellent idea in general.

You have an oil pressure gauge and are now becoming familiar with the pressure-to-temperature relationship. As long as you keep in mind that the main and rod bearings are most vulnerable at those pressure extremes, you can safely experiment with different viscosities.

Keep in mind that at those cold-start temps you are getting high pressure because the clearance between cranskshaft and journals is at its minimum and the oil is thicker. Just be gentle with the engine until the pressure drops to the approximate 10 PSI/1000 RPM rule of thumb.

[mxm64]

GT86 Manual offers 5w30 as an option, so don't see why this would Not be safe in NA car also?



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[Ultramaroon]

Originally Posted by mxm64

GT86 Manual offers 5w30 as an option, so don't see why this would Not be safe in NA car also?

Oh, it's fine. Just don't beat on it while it's cold. You'll take a slight hit on gas mileage.

[mxm64]

Changed oil to 0w30 Mobile 1 and noticed slightly increased pressures when warm. But now also noticed new phenomenon.
When driving and have higher load/throttle and AVCS value, the pressure drops at same the rpm. 25psi at 3k cruising light throttle/AVCS and then full throttle in 5th gear at 3k pressure drops to 15psi. Oil temp around 200F.
I did not notice this with 0w20 oil. Is this normal? Has me concerned AVCS may not function properly with thicker oil? I still have the Max Tow Gauge sensor installed in the oil gallery.

https://docs.google.com/spreadsheets...it?usp=sharing

[Ultramaroon]

Something doesn't smell right. I'll stop there because this is out of my tax bracket. Did the tech tell you where the 7-51 spec came from? Is that PSI?
@Decay107, what pressures do you see?

[Decay107]

Originally Posted by mxm64

Changed oil to 0w30 Mobile 1 and noticed slightly increased pressures when warm. But now also noticed new phenomenon.
When driving and have higher load/throttle and AVCS value, the pressure drops at same the rpm. 25psi at 3k cruising light throttle/AVCS and then full throttle in 5th gear at 3k pressure drops to 15psi. Oil temp around 200F.
I did not notice this with 0w20 oil. Is this normal? Has me concerned AVCS may not function properly with thicker oil? I still have the Max Tow Gauge sensor installed in the oil gallery.

https://docs.google.com/spreadsheets...it?usp=sharing

I see about 100 or so cold, 60 or so during highway cruise and maybe 80 or so to redline. On track I usually see around 60 +-10. This is all on 5w30 with the pressure read at the location recommended by the factory. I've just changed back to 5w-20 but do not have enough data yet to make a judgement.

Anyway you should measure from the front oil port just below the oil filter (location of stock pressure switch), this is where the pressure is meant to be read (per the manual) and indicates total system pressure just after filter and any oil cooling. Top of the block is somewhere mid stream so there is no defined pressure range, it may also be affected at that point by any number of upstream variables including AVCS.

But my input here is, as long as the pressure at the pump output is within the normal defined range the motor is operating as intended, unless there are some other symptoms?

Now on to your pressures, 60psi at 6k does seem a little low (should be over 70, tech is wrong on the 51 number), how do you measure temperature?

[mxm64]

I question the tech's readings on the shop receipt. I challenged the service manager but he stands behind the tech. This is why I am doing my own testing.
The last 60psi I measured was from the front timing cover port where the service manual says to connect a guage into the original pressure switch location. I used a cheap Harbor Freight mechanical gauge so calibration is always in questioned. Oil temps are measured with my OFT using factory sensor. I ordered an adapter to fit my digital dash pressure gauge sensor into the front cover. Will update the thread when I have new numbers. If the pressure still drops in that location during heavy engine load, I feel I need to switch back to 0w20 to be safe?

Sent from my Nexus 6 using Tapatalk

[Decay107]

Originally Posted by mxm64

I question the tech's readings on the shop receipt. I challenged the service manager but he stands behind the tech. This is why I am doing my own testing.
The last 60psi I measured was from the front timing cover port where the service manual says to connect a guage into the original pressure switch location. I used a cheap Harbor Freight mechanical gauge so calibration is always in questioned. Oil temps are measured with my OFT using factory sensor. I ordered an adapter to fit my digital dash pressure gauge sensor into the front cover. Will update the thread when I have new numbers. If the pressure still drops in that location during heavy engine load, I feel I need to switch back to 0w20 to be safe?

Sent from my Nexus 6 using Tapatalk

If pressure drops like that in the port on in the timing cover, you have something strange going on. I run 5w-30 and my pressure behaves as expected, no strange dropouts or load dependent changes.

[mxm64]

Moved electronic gauge pressure sensor to timing cover factory pressure switch location. Pressure are now 8 - 9 psi per 1k rpm at 180F oil temp with 0w30. And pressure increases with rpm as expected no matter AVCS advance or engine load.

[Ultramaroon]

Originally Posted by mxm64

Moved electronic gauge pressure sensor to timing cover factory pressure switch location. Pressure are now 8 - 9 psi per 1k rpm at 180F oil temp with 0w30. And pressure increases with rpm as expected no matter AVCS advance or engine load.

That is interesting. Even though I agree with @Decay107's assertion about the correct point to measure, I did not expect there to be a significant difference.

[Decay107]

Originally Posted by Ultramaroon

That is interesting. Even though I agree with @Decay107's assertion about the correct point to measure, I did not expect there to be a significant difference.

Wonder how if any of the guys running high viscosity and reading pressure there have seen it? Dezoris had a video a while back that showed pressures at different weights and temps, think he was reading atoil galley plug but I don't remember seeing this.