Oil pressure is higher after oil change
 

Changed out the Mobil 1 5w-30 for Redline 5w-30. Also changed from a larger filter (what you’d use on a Nissan v8) to OEM size Fram oil filter. Oil pressure at 180° used to be ~35 psi but now I’m seeing 40-45psi. Could this be that Redline thins out less as it heats up, causing the higher pressure reading? Did I get an unusually restrictive filter? This is probably nothing to worry about, but hey figured I’d ask around.

FYI, my pressure sensor is located pre oil cooler AND pre oil filter.


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Question: After 30-40 minutes of normal driving, assuming Oil Temp is still at 180, Does the pressure still read 40-45 psi? For me this is about how long it takes for my oil to be fully warmed up after a cold start. I'm using Mobil 1 5w-30 and a K&N HP1008 filter. My Pressures at idle after a drive with oil temps 180-190 are as you say 30-35 psi. Oil temps would need to get up to 215-220 before my idle psi drops to around 25 psi.

Yup oil pressure is 40-45psi at 180° after 30 minutes of driving last night. My car hits ‘steady state’ oil temp around 180° with the 34 row oil cooler.


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Oil pressure is higher after oil change
 

So Redline 5w30 viscosity when hot is 11.9 cSt. Mobil 1 5w30 is 10.2cSt. This means Redline is well above average in terms of 5w30 thickness, and Mobil 1 is below average.
Source: http://www.pqiamerica.com/viscosity.htm

Now that I think about it, I wonder if I had my AC on as well which would’ve bumped up my idle a bit and thus the pressure

Between Redline being thicker and my AC possibly being on, I think I just answered my own question and there’s no need to worry.


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Well your idle with the AC on should be a bout the same with just about a 4-6% increase in load. On the contrary having the AC on will lower coolant temperatures a bit so this will affect the oil cooler as well since the fans are running constantly.

Though the filter shouldnt be so much of a difference you'd have to revert to the stock filter and compare the data to conclude that it's the oil.

Either way I've heard nothing but greatness coming from redline.

You may want to move your pressure gauge to the 1/8 BSP port on the engine block.

The engine oil pressure inside the engine = 35psi - (oil cooler & lines pressure drop) - (oil filter pressure drop)

If my engine is "normal" it seems like your oil pump needs an extra 10-15 psi to push the oil through your oil cooler and filter @ 180F

With that in mind, if your actual engine oil pressure is 10 psi due to a failing galley gasket, your gauge might show 20-25 PSI, which hides the problem and may result in a spun bearing / new engine... and no one wants that!

Oil pressure is higher after oil change
 

I do plan to eventually relocate the sensor to tee off the oil return line to the block. But for now I’m not concerned that it’s giving me a false reading. Pressure drop in the filter should be 1-2 psi and in the cooler probably about the same at idle. Therefore I think anything over 30 for a pressure reading is totally normal.

But to your point… reading pressure after the cooler and filter would giving me the reading that really matters… what’s going into the engine.


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My Oil Pressure is read at the Sandwich Block the Cooler lines attach to, so not sure if it is pre or post cooler. I would guess Pre-Cooler though. As I interpret the Sandwich plate design, the oil gets filtered before it gets any cooling. Checked my pressure last night and 25psi at idle with 189 degree oil temp. If I recall correctly, Nissan calls for no less than 14psi at idle and 43 psi at 2000 RPM (@180 oil temp). Your stats are impressive to say the least. A pretty strong argument to switch to the Redline in my book. I am also considering the Motul engine oil though. I use them for all other lubricants and fluids, where possible.

The centre hole in the oil filter is the exit of the filtered oil and that goes directly into the engine.

For anyone with a sandwich plate and oil cooler the oil flow is this:
• Oil pump
• Sandwich plate
• Oil cooler
• Engine oil filter
• To engine

This is a good setup as the oil filter is the "last in line". (love that song by Ronnie James Dio!!)

Just be aware your indicated oil pressure is not the oil pressure inside the engine (after the oil filter)

The stock design flow is:
• Oil pump
• Engine oil filter
• To engine

Smaller filter, higher pressure. One of the reasons Nissan did away with oil pressure gauge in the 370Z was people going into dealerships under warranty thinking they blew gallery gaskets with low pressure when Joe Lubejob slapped a bigger or different filter on or swapped out for thin-mint oil

So what's the consensus run smaller for pressure or larger for enhanced filtering capacity?

Run a factory Nissan filter.

Hope nobody will mind if I add some more questions to this thread....
I'm planning an oil cooler installation, as well as adding a pressure gauge just to make sure I have my oil hoses in check. I was thinking of a mishimoto oil cooler and sandwich plate which should have a pressure sensor plugin hole. If I use this, do I get any realistic reading of the engine pressure or is it meaningless because it's all pre-oil cooler?

Thanks for the info.

Meaningless? No not at all. Just be aware that your pressure going back into the engine will be some amount lower than what you’re reading. The pressure drop really isn’t THAT large through the cooler and filter (at least from what I’ve researched), but just be aware of it.


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Stay away from the miSHITmoto kit. You have been warned.

Tee off the stock engine oil pressure sensor. It's the best way.