Spark Plug Replacement — 3.8L and 3.6L

Difficulty 2/51–2.5 hrs$35–902007-2018

The 3.8L uses two plugs per cylinder (12 total) and the 3.6L uses one per cylinder (6 total). Both are coil-on-plug. Gap and torque matter: 3.8L at 0.043", 13 ft-lb; 3.6L at 0.043", 13 ft-lb. Change interval is 30K (3.8L copper) or 100K (Pentastar iridium).

The 3.8L V6 (2007–2011) and the 3.6L Pentastar (2012–2018) take very different approaches. Both are coil-on-plug systems, but the 3.8L runs a dual-plug-per-cylinder setup for emissions — two plugs, two coil packs on each side of each cylinder, twelve plugs total. The Pentastar runs one plug per cylinder with a single coil-on-plug at each, six total.

3.8L plug choice. Mopar spec is NGK ZFR5LP-13G platinum, gapped at 0.043". You can run copper plugs (NGK ZFR5N) for cheaper if you don't mind changing them every 30K miles. The platinum plugs go 60K. Iridium upgrades are pointless on this engine — the 3.8L doesn't reward fancier plugs and they cost 3x more.

3.6L plug choice. Mopar spec is the Champion RE10PMC5 (also sold as NGK PLZKAR6A-11), iridium, gapped at 0.043". Service interval is 100K miles. Do not regap iridium plugs — the precious metal tip is thin and chips. They come pre-gapped from the factory; check with a wire gauge but don't bend.

Access. 3.8L driver-side plugs require pulling the intake plenum on the rear three. Plan for 2+ hours if it's your first time. 3.6L is dramatically better — pull the engine cover, disconnect 6 coil connectors, remove 6 coil bolts, and the plugs are right there.

Torque is critical. Pentastar uses aluminum heads. Overtightening strips threads, undertightening lets the plug back out under combustion pressure. Use a torque wrench. 13 ft-lb on both engines.

Steps

  1. Engine cold. Disconnect negative battery cable.
  2. 3.6L: Pull the engine cover (friction fit). Disconnect each coil connector. Remove the 10mm coil hold-down bolt. Pull each coil straight up.
  3. 3.8L: Same idea but you have a coil on each side of each cylinder. Driver-side rear three require intake plenum removal — pull the 4 intake bolts and lift it aside, leaving fuel lines connected if possible.
  4. Use compressed air to blow debris out of the plug well before pulling the plug — dirt falling into the cylinder is a real risk.
  5. Use a magnetic or rubber-insert plug socket to back out the old plug. Check the porcelain for cracking and the electrode for excessive wear (gap should still be within 0.005" of spec).
  6. Verify gap on new plugs with a wire gauge (3.6L: 0.043"; 3.8L: 0.043"). Do not regap iridium.
  7. Skip anti-seize on factory-coated plugs (most modern plugs come coated). If you must use it, a pinhead-sized dab on the threads only — never on the tip or seat.
  8. Thread plug by hand until snug, then torque to 13 ft-lb.
  9. Apply dielectric grease to the inside of the coil boot. Install coil. Torque the 10mm bolt to 60 in-lb (5 ft-lb).
  10. Reconnect coil connectors. Reinstall engine cover. Reconnect battery. Start, listen for misfire.

Why it works

Trade-offs

Tools required

Parts

PartVendorEst. price
NGK ZFR5LP-13G platinum (3.8L, qty 6)NGK~$35
NGK PLZKAR6A-11 iridium (3.6L, qty 6)NGK~$75
Champion RE10PMC5 OEM Pentastar plugChampion~$60

Sources

Related

Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.

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