Fluctuating Oil Pressure

[Trinny]

I've noticed recently that my oil pressure guage will fluctuate based on RPM. For example, at idle, the pressure needle will hover just above the bottom line of the guage. As RPM's build, the guage needle will rise to where at 2000-3000 rpm, it will be between the "normal" operating range on the guage. I'm not sure what the PO used, but I recently changed to M1 5w-30 synth. I do have a small leak near the front of the engine, approx. 1 drop per day. I have not noticed a significant loss of oil from driving. I seem to remember the pressure fluctuating within normal ranges when I bought the truck, but it seems to have become more dramatic.

Any ideas what could cause the fluctuating oil pressure?

 

[nyk438]

It's normal.

 

[rolliges]

Changed the oil and filter last week and had this happen the past few days. Spent all morning on this board searching for an answer. Found a decent one; you can too.

Search for a post by robbie called "oil pressure and destruction." Don't worry the title is misleading.

Happy searching,

 

[OGBeno]

I've noticed recently that my oil pressure guage will fluctuate based on RPM. For example, at idle, the pressure needle will hover just above the bottom line of the guage. As RPM's build, the guage needle will rise to where at 2000-3000 rpm, it will be between the "normal" operating range on the guage. I'm not sure what the PO used, but I recently changed to M1 5w-30 synth. I do have a small leak near the front of the engine, approx. 1 drop per day. I have not noticed a significant loss of oil from driving. I seem to remember the pressure fluctuating within normal ranges when I bought the truck, but it seems to have become more dramatic.

Any ideas what could cause the fluctuating oil pressure?

As the truck works harder the oil flows faster and thus increases oil pressure. As you slow down and come to idle, the engine is pushing through less oil, hence lower oil pressure.

That said, the type of oil you use will also make the fluctuations arrive at different points. If you are using a thicker oil, it will be higher on the pressure gauge. If you run thinner oil it will go up lower on the pressure gauge and go down farther on the low end at idle.

Do a search with the user name "cary" or "raventai"--both have written tons of stuff about oil pressures, different viscosities, etc.

Try this: Run the Mobil 1 5-30 syth for one cycle and then switch to Rotella 15-40 and check out the difference. I run the 5-30 during the winter and the 15-40 during the summer.

Cheers.
-onur
Akron, OH

 

[nyk438]

Does it matter if your oil pressure is lower? I use dino oil 10w30 in my 3FE.

 

[fuelgeddes]

Mine does this too. But just keep your eye on it. If it doesnt read anything pull over and stop !

 

[Elijah]

Yeah, you're oil pressure is normal. Especially with the switch to synthetic 5w-30, you'll notice a lower reading in general.

 

[Trinny]

Thanks for the replies. I did notice on the way home today that when cold, the pressure read, and stayed, in the normal range, probably due to the oil being cold. Once the engine warmed, however, the pressure fluctuations became greater, so at idle, it was just above the bottom line. This supports the theories of beno and boekppl.

So, if the oil pressure reads lower using synth 5w-30, does this mean that there is less pressure on seals and gaskets? Or, by running with lower pressures is there a chance of not lubricating the engine as well (i.e., oil doesn't flow as well)? Can't believe I'm asking this, but would semi-synth (or heavier synth) theoretically be a better option? The reason I ask is that I don't see the same results in my Camry or my Tundra. Although, I did see it in my old Sequoia.

 

[OGBeno]

This has been hashed and re-hashed about three million times here on the 80's section and on other sections as well.

Just do a search under username "cary" and "raventai" and you'll get three weeks of reading about oils, synths vs. dino vs. semi-synths, oil pressures with different grades, etc.

Here's just a few I found:

https://forum.ih8mud.com/showthread.php?t=19925

https://forum.ih8mud.com/showthread.php?t=10995

https://forum.ih8mud.com/showthread.php?t=10090

https://forum.ih8mud.com/showthread.php?t=61822

https://forum.ih8mud.com/showthread.php?t=50319

https://forum.ih8mud.com/showthread.php?t=38859

https://forum.ih8mud.com/showthread.php?t=28105

https://forum.ih8mud.com/showthread.php?t=4964

https://forum.ih8mud.com/showthread.php?t=29785

https://forum.ih8mud.com/showthread.php?t=27295

https://forum.ih8mud.com/showthread.php?t=20016 (this is a good one)

https://forum.ih8mud.com/showthread.php?t=16184

Enjoy the reading.
-onur
Akron, OH

 

[BOZ]

Yes, this is normal. I ran closer to 3/4 with normal 10/w30 and switched to synth mobile one and it dropped. I changed over to 5w/30 in Whitehorse BC to handle the cold and it dropped even more. I run about 2k rpms at 60mph at about 1/2 pressure gage or less.

Boz

 

[Trinny]

...do a search under username "cary" and "raventai" and you'll get three weeks of reading about oils, synths vs. dino vs. semi-synths, oil pressures with different grades, etc.

Thanks Beno! I did do a search for oil pressures, fluctuation, etc., but not on cari or raventai. Time to do some homework.