C172 EXPERIENCES LOW OIL PRESSURE WHILE HOLDING IN VMC CONDITIONS. REQUESTS EXPEDITED HANDLING TO ARPT.

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TRACON HANDED ME OFF TO THE ZZZ TWR; FROM WHOM I REQUESTED AN SVFR RETURN. THE TWR INSTRUCTED ME TO HOLD IN VMC 5 MI E OF THE ARPT UNTIL CLRED TO CONTINUE TO LAND. I ORBITED AT 2000 FT; 2200 RPM; APPROX 85 KTS; IN A SHALLOW BANK. AFTER ABOUT 10-15 MINS I NOTICED; DURING AN INST SCAN; THAT THE NEEDLE ON MY OIL PRESSURE GAUGE WAS ABOUT 1/4 INCH BELOW THE GREEN ARC AND MY OIL TEMP GAUGE WAS 'RED LINED.' BECAUSE OF THE DECREASING LIGHT; HAZE; AND LOW ALT; I DETERMINED I COULD NO LONGER WAIT NOR DIVERT TO ANOTHER ARPT. I CALLED THE TWR AND ADVISED THEM OF MY LOW OIL PRESSURE AND HIGH TEMP; REQUESTING AN IMMEDIATE RETURN FOR LNDG. THE TWR VECTORED ME TO INTERCEPT THE FREEWAY WHICH DEFINES THE NORTHERN GEOGRAPHIC BOUNDARY OF ZZZ. I FOLLOWED THESE INSTRUCTIONS AND LANDED WITHOUT FURTHER INCIDENT. WHILE I HAD NOT EXPLICITLY DECLARED AN EMER; THE TWR TOOK THE INITIATIVE TO 'ROLL THE EQUIP;' WHICH FOLLOWED ME TO THE PARKING AREA OF MY FLT SCHOOL. ENG TEMP REDUCED TO NORMAL DURING FINAL APCH AND TAXI (LOW RPM); OIL PRESSURE INCREASED TO JUST BELOW THE GREEN ARC. INSPECTING THE COWLING INTERIOR AND EXTERIOR; FUSELAGE BELLY; AND UNDER THE ACFT REVEALED NO OIL LEAKS. THE OIL LEVEL WAS 6 QUARTS OF 7 MAX; 5 MIN DURING PREFLT. I HAD FLOWN THIS AIRPLANE THE PREVIOUS DAY WITHOUT NOTICING ANY PRESSURE OR TEMP ANOMALIES. THE AMBIENT TEMP WAS ABOUT 18 DEGS C AND LOWER DURING THE FLT.