Mechanic can gauge the source of oil pressure problem. - Richmond.com
I have a 2006 GMC Envoy XL with 227,000 miles. After sitting in the garage overnight, when I start it, the oil pressure gauge will drop, and the oil warning lights come on. If I leave it in park and keep the engine revved up, then the oil pressure will go up. Two blocks from the house is a... Why does it have oil pressure after it’s warmed up but not after sitting overnight. Normally, oil pressure is higher when you first start your car, because the oil is cold and more viscous. So why the pressure would start low and then improve as you drive is a mystery. Yeah, I know, that’s why you wrote to me. If the reading on your gauge is accurate, then yes, you are damaging the engine by driving it with low oil pressure. So the first thing you need to do is find out if your oil pressure really is low, or if you’re getting an incorrect reading. In the morning, he’ll put his own oil gauge on it, and start it up. If his gauge tells him that your oil pressure is exactly what it’s supposed to be, then he’ll know that either your truck’s oil gauge or your oil pressure sending unit is no good. That’s a little sensor that plugs into the side of the engine, reads the pressure and sends that information to the gauge and the idiot lights on the dashboard. Source: www.richmond.com
