Sooo some of you havent heard i bought a 95'S500 and ijsut got done rebuilding the motor. We finished the installation this morning and everything was fine. As of now i took it for a short test drive and i notice the Economy gauge is out of whack.. its is not responding like how it normally does when you step on the pedal. Now i see that the oil pressure gauge level has dropped and is not holding pressure at (3)psi like how it normally should. I went ahead and use the Castrol 5-30 Synthetic motor oil. Now im wondering if its the synthetic oil that is causing me to lose oil pressure? Or maybe its the oil pressure switch. I changed almost every internal part besides the oil pump and the oil pressure switch.