You'll need a service manual to give you the figures for minimum oil pressure. That manual will also tell you how to check the oil pressure (by attaching a presure gauge to the threaded opening for the oil pressure sender). The manual will also tell you whether the timing chain tensioner for this motor is actuated by oil pressure or not. Some motors are, and some are not. If the tensioner is actuated by oil pressure; and if the presure got low enough; it could cause the timing chain to jump.