AEM Oil Pressure Gauge Most cars today rely on what we call idiot lights to warn you of some critical engine parameters - the most critical next to water temp is oil pressure. Most factory warning lights don't come on until oil pressure is under 20 to 30 psi. When running at high RPM, that is way too little oil pressure to protect your main and rod bearings. Run a few laps like that, and you may have to rely on hearing a rod knock once in the pits or you may ventilate your block. We have found even running 1/2 a quart low at a track like Willow Springs with its long Turn 2 sweeper can result in wild swings in oil pressure. Know if you are flirting with disaster by running an AEM Oil Pressure Gauge.