Dana 44 Differential Fluid Change — Jeep Gladiator JT
Difficulty 2/51–2 hrs$30–802020-2024
The Gladiator JT runs Dana 44 axles front and rear from the factory — the same robust architecture Jeep has used in Wranglers for decades, with the same fluid change intervals that most owners run past due.
Differential fluid breaks down from heat, water intrusion, and metal wear particles suspended in the oil. On a trail rig that's done creek crossings or driven through standing water, that interval shortens significantly because water can enter through axle tube vents. Factory spec calls for a fluid change at 15,000 miles or when the vehicle has been submerged past the axle housings — whichever comes first. Most experienced Gladiator owners drain both diffs at 10,000 miles or annually, especially if the rig sees regular mud or water.
The JT's front axle also houses the front locking differential on Rubicon trims. The fluid change procedure is identical — Eaton's factory locker is a helical-gear design that runs in gear oil and doesn't require special handling during the drain/fill.
What fluid: The factory spec is 75W-140 synthetic gear oil with a limited-slip additive. The Rubicon's Tru-Lok lockers and Eaton helical unit are compatible with this spec. Using straight 75W-90 without the LS additive can cause the limited-slip functionality to chatter. If you see "GL-5" on the label and the spec says 75W-140, you're in the right range — verify it explicitly includes friction modifier or add it separately.
Stripped fill plugs: The fill plug threads into cast iron and can corrode or cross-thread. If it turns but won't tighten, the threads are gone — the cover needs replacement or a helicoil insert.
Water contamination: Milky or grey fluid means water has been in the diff. One fluid change may not clean it fully. A second change at 500 miles after the first is good practice when water contamination is found.
Over-RTV: A thick bead of RTV can squeeze inward and form debris in the diff oil. Thin bead, even application.
Rear locker vent: Make sure the axle vent line is clear and unobstructed after the change. A clogged vent is how water gets in during creek crossings.
Mopar factory fluid (75W-140): ~$16–20/qt. Two quarts covers both axles with some margin. This is the spec-correct choice if you want to avoid any compatibility guesswork.
Red Line or Amsoil 75W-140: ~$18–24/qt. Equivalent quality, better availability at most auto parts stores.
RTV silicone (Loctite 598 or Permatex Ultra Grey): ~$8–12. One tube does several gasket applications.
Shop rate for a differential fluid change is typically $80–150 per axle, plus fluid markup. Both axles DIY comes in well under $60 with quality fluid.
Steps
Park on a level surface. Let the axle cool for at least 30 minutes after driving — drain temperature should be warm, not scalding.
Support the vehicle on jack stands. You don't need to get the axle high, enough to work under it safely. Never rely on a floor jack alone.
Place your drain pan under the front Dana 44. Locate the fill plug (passenger side of the differential housing, roughly 4 o'clock position) and loosen it first — this prevents the situation where you drain the fluid and then can't break the fill plug. If you can't loosen the fill plug, stop and figure it out before draining.
Remove the drain plug or, on axles without a dedicated drain, remove the diff cover. The JT front Dana 44 does not have a threaded drain plug — you'll remove the cover using the 10 bolts around its perimeter (10mm or 3/8" drive socket).
Allow the old fluid to drain completely. The outgoing fluid tells you something: dark metallic flakes suggest accelerated wear; milky grey oil means water intrusion happened; dark brown is normal for used gear oil. Document it with your phone camera for reference.
Inspect the cover gasket. The factory uses an RTV gasket on most JT diff covers. Clean both mating surfaces with a wire brush and solvent — no old gasket material, no debris. Apply a thin, even bead of Ultra Grey RTV (about 1/8" diameter) to the cleaned cover face.
Reinstall the cover and torque the bolts to 30 ft-lbs in a cross pattern. Don't overtighten — the cover is thin aluminum on some trims and the threads strip at torques above 35 ft-lbs.
Let the RTV cure for 15–20 minutes before filling.
Fill the differential through the fill plug hole with 75W-140 synthetic. The correct fill level is "at or slightly below the fill hole" — when you insert a finger and feel fluid, you're at the right level. The JT front Dana 44 holds approximately 2.2 pints. The rear Dana 44 holds approximately 3.5 pints.
Reinstall the fill plug. Torque to 25 ft-lbs. Wipe the housing clean.
Repeat on the rear axle — same procedure, same fluid spec, same torque values.
Drive for 15–20 minutes, then park and inspect both covers for leaks.
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.