Automobile Repair/Nissan/Maxima (4th Generation)/Changing the Spark plugs
What Type of Plugs to Get? 
From my fellow Maxima enthusiasts. Quite simply, the platinum tipped NGK plugs that come stock with the Maxima are great plugs. You can try those other aftermarket plugs, but you may be asking for trouble. I know of someone directly who put those Bosch +4 plugs in their car and caused some serious damage. (Its never a good idea to install a domestic made plugs in a foreign made card) So stick with the NGKs. Also, please note that NGK spark plugs come in standard, hot, and cold temperature types, which refer to the relative temperature the plug operates at during operation of the vehicle. For all-around use, select the "standard" temperature plug. In contrast, the "cold" plugs run cooler and are better suited for cars running at higher speeds and loads. "Hot" plugs run slightly hotter than your "standard" temperature plug, and are best suited for vehicles used intermittently or at generally slow speeds (around town, idling, etc.). A hotter plug temperature burns off the increased deposits generated by slower operating vehicles.
Tools/Parts needed 
- A 5/8 spark plug socket.
- An 10" socket extension
- A universal joint for the extension and socket
- metric sockets
- 4mm allen wrench
- You may also find that a stick with a magnetic tip can come in handy.
- Dielectric Tune-up Grease
- Using a 4mm allen wrench, remove the cover by unscrewing four allen screws as shown by the red arrows.
- You'll now see the exposed coils. Disconnect the wires to them. The connections are shown by the green arrows. The far right is already unhooked.
- Using the above picture, unscrew the two bolts holding each of the ignition coils in place. (Shown by the red arrow).
- With the bolts removed, pull out the coil.
- With the coil removed, you can see the spark plug: Using your extension, spark plug socket, and universal joint, unscrew and pull out the spark plug.
- Do this for all 6 spark plugs. Here's the rear bank of 3, shown with the green arrows.
- That rear spark plug towards the middle of the engine bay is tough to get to. Make it easy on yourself and remove the two objects blocking it (shown by the blue arrows above.) Removing them is easy. The plastic ring is held by a single bolt and the EVAP canister purge volume control valve further up is held by two bolts. Unbolt both and just move them aside, no need to remove/disconnect wires or tubing.
- This line is incorrect. Do not coat with anti-seize , as you may create an engine misfire by easier path to ground through the metallic anti-seize, rather than through the spark plug. Coat the threads of each spark plug with anti-seize and insert it back in. For my 96 Maxima, the torque specs for the spark plugs are 14-22 ft-lbs.
- Coat the inside of the coil where it makes contact with spark plug with a thin layer of dielectric tune-up grease. This helps minimize corrosion.
- Reinsert the ignition coil. Secure it with the 2 bolts.
- Repeat this procedure for all the ignition coils.
- Don't forget to put back the EVAP valve and the plastic ring.
- Reconnect the coils.
- Put the cover back on the front 3 coils.
- Start the car and test the engine.
- That's It! You're DONE!
Well...not so fast. Some Maximas have the rear-spark plugs buried under an aluminum intake plenum, which must be removed to access the rear-bank spark plugs. Removing it requires 1) marking (with tape) and disconnection of about 12 different hoses connected to it, and 2) removal of the upper intake plenum itself which has a specific bolt tightening sequence and torgue requirements. You will need to be prepared to have a new plenum gasket, and gasket sealant *before* you start the work. The best explanation of removing this piece is found in the "Haynes Repair Manual - Nissan Maxima 1993 - 2001" by Bob Henderson and John H. Hayes. ISBN: 1-56392-450-1.