How many ft lbs of torque when installing spark plugs on 1999 Cadillac deville?

The recommended torque specification for spark plugs on a 1999 Cadillac DeVille is 15 ft-lbs. However, always double-check your owner's manual or a reliable repair manual specific to your vehicle's engine (Northstar or other) as slight variations can exist. Using a torque wrench is crucial to avoid over-tightening and damaging the threads.