How do you change spark plugs in a 1998 Oldsmobile Intrigue?
For a 3.5L engine the plugs are under the coil packs on top of each head. The front side is pretty easy to access, 7 bolts and it comes off. Unplug the coil pack connector on the end to remove the coil pack from the engine. The back side is the same, only you can't see it as easy. The plugs are down in the head, connected to the coil pack by a rubber sleeve with a spring in it (there are no plug wires). This is commonly called COP (Coil Over Plug). Buy the original AC Delco (actually NGK) plugs, as the Champions, Split fires, and other platinum brands will not work as well for some reason. Torque each plug to 18 ft-lbs, and make sure the coil packs are thoroughly checked for cracks and electrical integrity before reinstalling. I tested my coils and they each had about 33 ohms between the coil and ground spring. Visually look them over for cracks or holes. The bad news - plugs are about $7 each, the coil packs are $300 each if you need one. I haven't tried a junkyard for coil packs, but I'd bet you could find them there. I also suggest removing the battery "hot" wire while you change plugs to avoid arc welding tools to your engine. Tools needed: 5/8 spark plug socket, 3/8 drive ratchet (flex head works better), socket extensions. Follow the spark plug wires to the spark plugs, unplug the wire one at a time and remove the plug. Gap new plug with the correct and gap and proceed to put new plug in. Be careful not to crossthred the plug. Repeat this procedure for all of them. One of the plugs is difficult to get to. On that particular plug, it might be easier going from underneath the car.