2000 catera started running hot and causing oil light to come on. Should the cooling fan behind the radiator be on when the engine is running or only come on when triggered by temp? also when temp rises above the half way mark only one of the front fans(drivers side) comes on and the one behind the radiator? yesterday was stuck in traffic and temp rose causing the fans to kick on but the oil pressure dropped into the red due to the temp and the oil light came on. when I got going the oil pressure increases on acceleration but the oil light stayed on. Is the engine temp causing the oil to thin too much? what is up with the fans? could it be a relay issue, if so which relay(s)?