AN CRJ100 PLT RPTS ERRATIC OIL PRESSURE INDICATIONS LED THE CREW TO DECLARE AN EMER; SHUT DOWN THE ENG; AND DIVERT TO NEARBY ARPT.

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AT FL360; DURING CRUISE; THE 4 ENG OIL PRESSURE WARNING MESSAGE CAME ON. THE FO WAS THE PF. WE RAN THE QRH PROC WHICH LED US TO AN ENG SHUTDOWN AND ABNORMAL SINGLE ENG PROC. OIL TEMP INDICATIONS WERE NORMAL AS WERE OIL PRESSURE INDICATIONS. HOWEVER; THE #2 OIL PRESSURE INDICATED 28-37 PSI WITH THE #2 THRUST LEVER AT FLT IDLE. IN COORD WITH MAINT (VIA RADIO) WE DSNDED TO A LOWER ALT TO SEE IF ENG INDICATIONS WOULD STABILIZE; AND THEY DIDN'T. AS WE LEVELED AT FL180; THE FO ADVANCED BOTH THRUST LEVERS VERY SLOWLY. THE MESSAGE CAME BACK; ACCOMPANIED BY ABNORMAL (ERRATIC) OIL PRESSURE INDICATIONS. WE CONTINUED WITH THE ABNORMAL SINGLE ENG QRH PROC. WE DISCUSSED ARPTS WITH OUR DISPATCHER. HE MENTIONED ZZZ; BUT THE LONGEST RWY WASN'T LONG ENOUGH. HE DETERMINED WE NEEDED 7920 FT AND THE LENGTH OF RWY 5 IN ZZZ1 WAS OVER 8100 FT. HE AGREED ZZZ1 WAS THE BETTER ARPT. THE QRH PROCS WERE COMPLETED; AS WERE ALL NORMAL CHKLIST PROCS. THE LNDG IN ZZZ1 WAS UNEVENTFUL. CFR VEHICLES FOLLOWED US TO THE GATE AND RPTED WHAT MAY HAVE BEEN MINOR SCORCHING. FOLLOWING ARR AT THE GATE; EXAMINATION OF THE #2 ENG SHOWED NO SIGNS OF ANY OIL LEAKAGE. HOWEVER; THE L AND R SIDES OF THE FUSELAGE; AFT OF BOTH PYLONS; WERE VERY DIRTY. DURING THE DSCNT; THE FLT ATTENDANT WAS NOTIFIED OF A POSSIBLE DIVERSION IF THE ENG DIDN'T STABILIZE AT A LOWER ALT. AFTER THE ENG WAS SHUT DOWN; SHE WAS NOTIFIED OF OUR DECISION TO LAND IN ZZZ1. FOLLOWING ARR AT THE GATE; I CALLED DISPATCH TO AMEND THE RELEASE. THE DISPATCHER TOLD ME HE USED THE WRONG DATA TO COMPUTE THE REQUIRED LNDG DISTANCE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT THEIR ORIGINAL DIVERT AND THE CLOSEST ARPT WAS ZZZ. HOWEVER; WHEN DISPATCH CALCULATED THE LNDG DISTANCE REQUIRED; AN ERROR WAS MADE. DISPATCH SAID THE RWYS WERE TOO SHORT AT ZZZ AND SO THEY PROCEEDED TO THEIR NEXT ALTERNATE LNDG ARPT. THE RPTR DID NOT REMEMBER WHAT THE CORRECTED DISTANCE WAS; BUT RECALLED THAT THEY COULD POSSIBLY HAVE GONE TO ZZZ HAD THE CORRECT LNDG DISTANCE BEEN GIVEN THEM INITIALLY.