Oil Gauge

[LoneWolf31]

Good evening everyone, well from day one, my oil gauge has been sitting this low when at speed and on cruise. It does go up when under acceleration but then goes back to the same spot when back at normal speed.. is this normal. I did check and it had plenty of oil but I was hoping after the first oil change it might go up a little.

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[Goldeneye36]

I've seen the same thing myself in my truck and wondered what these new digital gauges are showing since I can't find the option to show PSI numbers anywhere.

In most cars the oil pressure gauge doesn't actually show pressure but is really based on a pressure switch/variable: above a set PSI the guage will show ~60% of max and below it will show 0% and throw a warning light/message. Typically only high performance vehicles or aftermarket gauges will show actual pressure, since it's normal for it to fluctuate with RPM and most people wouldn't know how to interpret that. Many cars don't even have an oil pressure gauge anymore and just have a light/message when it gets below a set PSI.

One thing I learned while skimming through the service manuals is that, at least on the 3.5L engines, the oil pump has a high and low setting depending on demand. My guess is maybe the digital gauge is reflecting that as it only seems to vary between 3 positions: 0%, 33%, and 66%.

 

[Dakar09]

And here I thought we were talking about the fuel gauge due to the post title ?

It's fine. No engines generate a lot of oil pressure at idle or steady cruise. As long as it goes up under revs and increased throttle and no warning lights come on, you're golden.

 

[LoneWolf31]

Man I apologize about the title lol, it was a long day! Thank you guys, I appreciate it.

 

[FaaWrenchBndr]

That’s completely normal. An excerpt from the service manual

Oil Pump

The engine lubrication system is of the force-feed type in which oil is supplied under full pressure to the crankshaft, connecting rod bearings, timing chain tensioners, piston oil cooling jets, turbochargers and VCT solenoids. The flow of oil to the valve tappets and valve train is controlled by a restricting orifices located in the each of the cylinder head oil galleries.

The lubrication system is designed to provide optimum oil flow to critical components of the engine through its entire operating range.

The heart of the system is a positive displacement internal 2-stage variable vane oil pump.

• The oil pump is mounted on the front face of the cylinder block.

• The rotor is piloted on the crankshaft post and is driven through flats on the crankshaft.
• Maximum system pressure is limited by an integral, internally-vented relief valve which directs the excess oil back to the oil pan.
• Oil pump displacement has been selected to provide adequate volume to make sure of correct oil pressure both at hot idle and maximum speed.
• The relief valve calibration protects the system from excessive pressure during high-viscosity conditions.
• The relief valve is designed to provide adequate connecting rod bearing lubrication under high temperature and high-speed conditions.
• 2-stage operation of the oil pump is controlled by an integral solenoid on the pump that will switch the pump between high and low mode operation.
• The engine PCM sends a 12v signal to the oil pump solenoid to switch the pump to low mode.
  Default is no voltage or high mode operation.
• Both low and high mode maintain required oil pressure to protect and maintain engine function al their specified speeds, engine load (trottle position), and engine temperature.
• Low mode operation is designed to maintain oil pressure between 20 to 30 psi at speeds from 1000 to 3000 rpm with low engine load and engine oil temperatures at normal operating conditions.
• High mode operation is at all other engine operating conditions.

 

[LoneWolf31]

Thank you sir, much appreciated

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