An A320 flight crew refused to accept an aircraft with an oil leak in the right engine due to the failure of maintenance to perform a run-up inspection.

Narrative

On walk around an unusual amount of oil was noticed on cowl on outer side of number 2 engine. Leak traced to a weep hole just aft of the ACOC Louvers. Maintenance Control was notified via Datalink. Contract Maintenance appeared and opened cowl. Some oil that had pooled on the cowl drained onto ramp and the inner cowl looked freshly wet with oil. Mechanic; who has had a lot of airbus training through other airlines; stated we would have to motor the engine. Maintenance Control also asked us to run while mechanic observed engine from outside. As a crew we declined to run engine. We then received a Datalink maintenance release with the 'leak' signed off. The Captain called Maintenance Control and expressed his belief that lack of a run-up crew caused the sign-off rather than an actual belief the plane was serviceable. Having actually observed the engine and the opening of the cowling; the Captain felt the sign-off did not reflect the true aircraft condition. A run-up and correct sign-off was required by the crew prior to flight. The crew was offered run-up pay by an unidentified person. We declined. Contract mechanic said he would not fly aircraft without run-up.