The 4.0L holds 6 quarts of 10W-30 (5W-30 in cold climates) with a spin-on filter. The 2.5L 4-cylinder holds 4 quarts. Drain plug torques to 25 ft-lb, filter hand-tight plus 3/4 turn. Job takes 30 minutes.
The TJ Wrangler runs either the 4.0L straight-six or the 2.5L AMC four-cylinder. Both use a conventional spin-on filter mounted on the lower passenger side of the engine block and a 13mm hex drain plug on the oil pan. The procedures are identical — only the capacity changes.
**Oil viscosity.** The factory called for 10W-30 above 40°F and 5W-30 below 40°F. Either is fine year-round in most climates. Some owners run 10W-40 in hot Southwest summers — the 4.0L wears in for the long haul on anything in this range. Phoenix and Las Vegas owners can safely run 15W-40 conventional. Don't run 0W-20 — the 4.0L has wider bearing clearances than modern engines and will burn it.
**Synthetic or conventional?** Conventional changed every 3,000 miles or full synthetic every 5,000 miles both work. The 4.0L is an old design with loose tolerances; it doesn't reward expensive synthetic the way a modern direct-injected engine does. The exception: if your TJ has 200K+ miles and burns a quart between changes, switching to a high-mileage synthetic blend with seal conditioner can stop leaks at the rear main and valve cover.
**Filter.** Any name-brand spin-on filter that fits the M22x1.5 thread works — WIX 51515, Mopar 5281090, FRAM PH3614, Mobil 1 M1-110A. The filter sits at an angle on the block; expect a quart of mess if you don't position the drain pan right.
| Part | Vendor | Est. price |
|---|---|---|
| 10W-30 or 5W-30 conventional or synthetic blend (6 quarts 4.0L / 4 quarts 2.5L) | any API SN+ rated | ~$24 |
| Mopar oil filter (spin-on) | Mopar / equivalent | ~$6 |
| Drain plug gasket | Mopar | ~$1 |
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.