47-59 Anyone else's Dolphin gauges read low?

[MiraclePieCo]

I have a set of Dolphin quad gauges that so are so common in these trucks, but the temp and oil pressure gauges read low. I know they're low because I've verified the readings with mechanical gauges. My temp gauge reads 140 degrees (with a 180 thermostat) and my oil pressure reads under 20 lbs (50 on a mechanical gauge). Dolphin tech suggested removing the thread sealant from the senders to improve the ground, but that didn't help. I know Dolphins are an economy gauge and I've read many snarky comments about their quality, but LOTS of guys are running them - anyone else have this issue?