[GK27V6]

Man I am glad you started this thread, I was considering doing the same just recently. I also have a cheap oil pressure gauge. I was a little suspicious of its readings eventually, so I bought a Glowshift one and put them side-by-side. The difference in readings is astronomical. According to my cheap gauge my engine is failing, often reading as low as 0.5 or even 0.3 bar (does that seem right to you?) Meanwhile, my GS says 17psi which as far as I understand is where it is supposed to be at idle fully warmed up with 5W30.

What's really messed up about this is my cheap gauge wasn't this way initially. It would fairly consistently be at 1.1 bar at idle, and sometimes go to 0.9 bar when things were more hot. Made sense to me, the engine I have in my car isn't in the greatest condition either (a temporary solution until I rebuild one of my old engines).

 

[GK27V6]

Some updates to add:

I've been giving thought as to why a cheap gauge may read incorrectly, and I get the feeling that it is related to temperature. Assuming the sensor is on an oil filter sandwich plate then it is fairly close to bank 2's header. I planned on creating a heat shield nearby to see if that would yield different results, but I get the feeling it's possible the sensor may have been damaged from heat exposure already (which may be independent of the header as well). I suspect that Glowshift's sensor is probably better heat-resistant (rightfully so).

As far as oil pressure itself goes, I recently came across a rule of thumb stating that the minimum oil pressure for most engines (so basically outside of dedicated racing applications) is 7PSI per 1000RPM. Which would be a good peace of mind if true.

 

[GK27V6]

I pray that it's not actually that low, but rather my choice of wire* combined with the cheap gauge and sensor will not be reporting accurately once thermal expansion properly sets in. It was showing 0.4 bar just before I snapped the picture.. and that should be below threshold for the pressure switch.
The sensor is also situated on a sandwich plate before the filter, so it should be reading slightly higher than actual.
Giving the car the slightest bit of gas would make the pressure reading shoot up to ~1 bar or so. Also letting it cool down by just a few degrees (down to 98 °C) made the reading go up to 0.7.
So hopefully (hopefully) it's just a case of cheap low-resolution gauge and sensor.

*) I've got 1.0mm² copper wires of about 3.5 meter going between the pillar and the sensor. The wires that came with the gauge were, from what I remember 0.5mm² or smaller, and likely aluminum. I'm guessing that the impedance in the system was rather precisely calculated during manufacturing and that my choice of wires has messed with that, so I'm likely losing resolution on the low and high ends of the scale. Yay for digital interpretations of resistance...

Well if it's anything like my oil pressure gauges then it likely is wrong. I guess the gauges (and their sensors) aren't that high of a quality, I'd recommend buying a different brand. Glowshift is a good balance between being good and relatively cheap. By all means buy from other more reputable brands if possible.

 

[GK27V6]

Well... Something might NOT be fine. I just dropped the oil, under 2000 km on it, and it is very sparkly. Hardly anything will stick to a magnet, but it looks like a lot of fine aluminum has been circulating around in the engine. Replacing oil and filter now but I might need to do another quick oil change in another 2000 km.. or find another motor. This one has likely had it.

Damn. I hope it's just from the cam timing chains digging into the heads/covers.