Engine Oil and Filter Change (4.0L I6)
Standard oil and filter service on the AMC/Chrysler 4.0L straight-six. Sump holds 6 quarts with filter; use 10W-30 conventional or synthetic for most climates.
The 4.0L is famously tolerant of oil choices, but it benefits from a clean change every 3,000-5,000 miles on conventional or 5,000-7,500 on a quality synthetic. Factory fill spec is 10W-30 for most ambient temperatures; 5W-30 is acceptable in winter and is what later FSMs list. Capacity is 6.0 quarts (5.7 L) with a new filter. Renix-era (1987-1990) and HO (1991-2001) engines share the same capacity and oil specs. The drain plug is a 15mm hex on the rear of the steel pan; the filter is on the passenger side of the block, mounted vertically, and tends to drip down the bellhousing if you do not pre-fill it. Many owners run Mopar MO-090 (long discontinued, replaced by FRAM, Wix 51515, or Mopar MO-285) for tight fitment under the manifold. Run the engine to operating temp before draining for fastest, cleanest evacuation. Re-torque the drain plug to 25 ft-lb against a fresh crush washer; the pan threads are aluminum on early years and easily stripped.
Steps
- Warm engine to operating temperature, shut off, set parking brake.
- Position drain pan under rear of oil pan and remove 15mm drain plug.
- While draining, remove old filter (passenger side of block) with filter wrench, watching for drips down the bellhousing.
- Wipe filter mounting surface clean; pre-oil new filter gasket; pre-fill filter with fresh oil to reduce dry-start time.
- Hand-tighten new filter 3/4 turn past gasket contact.
- Install drain plug with new crush washer at 25 ft-lb.
- Add 6.0 qt fresh oil, run for 30 seconds, shut off, check level after 5 min settle.
Why it works
- Cheapest insurance against engine wear
- Tolerant engine accepts any quality oil
Trade-offs
- Filter location drips on bellhousing/oxygen sensor connector
Tools required
- 15mm socket or hex driver
- oil filter wrench
- drain pan
- funnel
- torque wrench
Parts
| Part | Vendor | Est. price |
|---|---|---|
| Oil filter (Wix) | RockAuto/NAPA | ~$8 |
| Oil filter (Mopar) | Mopar | ~$10 |
| Motor oil 10W-30 (6 qt) | any | ~$25 |
| Drain plug crush washer | Mopar | ~$1 |
Sources
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Written and maintained by an AZ wheeler and driveway wrencher. How we source guides. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.