The intake manifold gasket may develop external engine oil leak. The manifold gasket will need to be replaced to correct this issue.
2000 Chevrolet Monte Carlo Problem Reports
RepairPal Verified 2000 Chevrolet Monte Carlo Problem Reports
The engine may start and stall with the security light flashing. This is commonly caused by a failed passlock sensor which is part of the ignition lock cylinder. A secondary cause could be the ignition switch itself. Worn contacts inside the ignition switch can cause voltage drop issues which can affect the passlock system. Proper diagnoses should be performed before replacing any parts.