I was recently driving on the highway and when I got off and was stopped at a stop sign, my oil pressure gauge went all the down until the "check gauges" light flashed on. When I began to drive again the pressure when back up to about half way. This has not happened since, but I'm still concerned. Based on what people have told me it is probabaly either the oil pressure sending unit or the oil pump. Does anybody have any idea which is more likely?