Differential Fluid Change — Dana 30/35/44

The TJ Wrangler shipped with three axle combinations: Dana 30 front on every model, Dana 35 rear on most non-Rubicon trims, and Dana 44 rear on the Rubicon (2003–2006) and some early Sahara/65th Anniversary builds. All three use the same basic service procedure — pull the cover, drain, scrape, reseal, refill through the fill plug — and all three benefit from a 75W-90 or 75W-140 synthetic gear oil. The most common mistake is changing the rear without checking what's actually back there. A Dana 35 has a smaller, more rounded cover; the Dana 44 cover is larger with a flatter bottom edge and 10 bolts.

Capacities differ. The Dana 30 front takes roughly 1.25 quarts (1.65 quarts on 1997 models, which used a slightly different housing). The Dana 35 rear takes about 1.7 quarts. The Dana 44 Rubicon rear takes 2 quarts. Buy 3 quarts if you've got the Dana 30 + Dana 35 combination, 4 quarts if you've got the Dana 30 + Dana 44 combination, and you'll have enough to refill both with a little left over for spillage.

Fluid choice matters more than the brand. 75W-90 GL-5 synthetic is the daily-driver standard. If you tow regularly or run 33s and above with regular trail use, step up to 75W-140 synthetic — the extra viscosity protects the ring and pinion under load. Skip the cheapest conventional 80W-90 unless you're flushing fluid every 15k miles. Rubicon Tru-Lok lockers do not require friction modifier. Trac-Lok limited-slip differentials (often found in the Dana 44 rear, some Dana 35s) require 4 oz of Mopar friction modifier (P/N 4318060AB) per fill, or the clutches will chatter on turns.

Most TJ axles do not have a drain plug. You drain by removing the rear differential cover, which means you'll also be replacing or reusing the cover gasket. RTV silicone (Permatex Ultra Black) is the OEM-style seal — clean both surfaces fully, lay a 3/16" bead around the bolt circle, install the cover, and let RTV cure 30 minutes before refilling. A Lubelocker reusable gasket is the upgrade — install dry, no cure time, and reusable for the next service.

Steps

1. Drive the vehicle for 10 minutes to warm the fluid for more manageable draining. Park level.
2. Place a drain pan under the differential. Loosen the fill plug FIRST with a 3/8 hex driver — if it's stuck or stripped, you need to know before you've already drained the axle.
3. Remove the differential cover bolts in a star pattern. Leave the top two bolts loose to control fluid release.
4. Crack the cover loose with a flathead screwdriver. Fluid will pour out — let it fully drain (5–10 minutes).
5. Remove the cover. Inspect the inside of the housing for metal chunks, glitter, or chipped gear teeth.
6. Wipe the housing interior, ring gear, and magnet (if equipped) clean of old fluid and debris. Reinstall the magnet.
7. Scrape old RTV from both mating surfaces with a plastic scraper. Wipe with brake cleaner.
8. Apply a 3/16" bead of RTV around the cover bolt circle, or install a Lubelocker gasket dry.
9. Reinstall the cover and torque bolts in a star pattern to 30 ft-lbs.
10. Wait 30 minutes for RTV to set (skip if using Lubelocker).
11. Pump 75W-90 synthetic gear oil through the fill hole until fluid trickles out the bottom of the fill hole. For Trac-Lok diffs, add 4 oz friction modifier before topping off.
12. Reinstall and torque the fill plug to 25 ft-lbs. Check for leaks after the first short drive.

Why it works

• Catches metal debris before it grinds the ring and pinion
• Cheap insurance — $40 in fluid vs. $1,500+ for a ring-and-pinion replacement
• Reveals worn gears, chipped teeth, or excessive backlash early
• Synthetic gear oil runs cooler under load

Trade-offs

• Messy job — fluid drips everywhere if you rush
• Requires RTV cure time (or a reusable gasket)
• Friction modifier is non-optional with Trac-Lok or it will chatter
• The Dana 30 front fill plug is often seized — soak in penetrant the night before

Tools required

• 3/8 ratchet
• 3/8 hex driver (for fill plug)
• 1/2 breaker bar
• fluid pump
• drain pan
• RTV silicone or cover gasket

Parts

Sources

• Wrangler TJ Forum — Fluid Capacities and Recommendations
• Motobilt — Jeep Wrangler Differential Fluid Capacity Chart

Related

• Oil Change — 4.0L and 2.5L
• Spark Plug Replacement — 4.0L
• All Jeep Wrangler TJ guides & tools
• Browse the full DIY database

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.