So I just got my car back from the shop today for head gasket replacements and a bunch of other seals and gaskets. I drove the car to and from work and everything ran great. I get in the car about 30 min ago for a night drive with the girlfriend and I notice my oil pressure is at 0 at idle. As soon as I give it gas the bars start to increase But at idle it sits at 0. The engine temp is fine and my the oil level is fine. I took it around the block and the oil pressure increases accordingly as I keep on the throttle. I let off the gas around 50mph and just glided and the pressuRe went down to 1 bar. Anyone know what's going on? No CEL, or weird noises either.