B737 pilot described an in flight engine shut down due to loss of oil quantity and pressure. The flight diverted to a suitable airport after declaring an emergency. The engine was recently installed on this aircraft.

Narrative

During cruise at 37;000 FT; engine instruments indicated low oil pressure (8 PSI) and 0 oil quantity. We immediately referred to the QRH and performed and in-flight engine shutdown. Air speed started to decay and a descent was initiated to FL250. FMS indicated a drift down altitude of 26;500. An emergency was declared with ATC. Aircraft was currently 80 NM from ZZZ which was considered the closest suitable alternate because of time required to descend; run checklist; and coordinate with Dispatch and the flight attendants. A controlled descent was planned and accomplished with no intermediate level offs until configuring at 2;000 FT on final approach. All checklists were completed and an uneventful; single engine ILS was flown. Fire coverage noted no abnormalities and escorted the aircraft to a jet bridge. Passengers were deplaned while arrangements were made for continued transportation. All involved agencies and services did an outstanding job in seamlessly assisting the crew in getting the aircraft and passengers safely to the gate.We were aware that the left engine was newly installed and there was a preflight discussion between the pilots on whether and engine change required any kind of functional check flight. Special attention was given to the engine during preflight but no discrepancies were noted. I am not familiar with how often engines are changed or removed from aircraft outside of 'C' checks. Functional check flights are required following those inspections for many reasons. If the number of engine changes outside of 'C' checks are rare; I wonder how many in flight shutdowns during revenue flights could be avoided if a functional or operational check flight was required following the hanging of a new engine.