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.
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.
| Part | Vendor | Est. price |
|---|---|---|
| Mopar Gear & Axle Lubricant 75W-140 (1 qt) | Mopar | ~$18 |
| Red Line 75W-140 NS GL-5 Gear Oil (1 qt) | Red Line | ~$22 |
| Amsoil Severe Gear 75W-140 (1 qt) | Amsoil | ~$20 |
| Loctite 598 Ultra Grey RTV Silicone | Loctite | ~$12 |
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.