Originally Posted by 40 to 332

Interesting. I can only share my experience. Initially, I installed an AEM oil pressure gauge (0-150 psi) based on a DIY posted by Spearfish some time ago. I removed the factory sensor and replaced it with the AEM sensor (I didn't bother installing a tee fitting to accommodate both sensors). With that set-up, I would see a reading of about 90-100 psi on a cold start, which dropped rapidly as indicated above by Rusty. At operating temperature (200F), I would see a reading of 18-20 psi at idle (no load). I can't recall exactly what the readings were under load at operating temperature, but they varied from about 70-85 psi at 2,500 to 3,000 rpm in 6th gear. I was running Motul 8100 X-Clean 5W-30 at the time. The next year, I switched to the Defi Red Racer Gauge (see above) since I preferred its appearance and it seemed to be more reliable. I re-installed the factory sensor in its original location and installed the Defi sensor on the oil filter sandwich plate (see above). I continued to run with the Motul oil (... only switched to the Nissan Ester oil at my last oil change when I took the readings shown in my earlier post). Anyway, I didn't notice any remarkable difference in readings after switching the sensor location. In fact, the readings remained virtually unchanged. I still continued to see a reading of 20 psi at idle under no load at operating temperature (200F).