Gen 2 Raptor Rear Differential Fluid Change (2017–2020, 9.75-in Axle)

Who this is for

This covers the Gen 2 Raptor's rear axle, the 9.75-inch unit used from 2017 through 2020, including trucks with the electronic locking differential. This is a cover-off job — you drain the whole sump by pulling the cover rather than through a separate drain plug, which is the normal method for this axle. The Gen 3 Raptor (2021+) carries the same differential family forward, so the mechanical steps here translate directly, but always confirm your specific fluid capacity against your own manual rather than assuming it carries over exactly — see the Gen 3 Raptor page for the rest of what changed.

Steps

1. 1

   Check the fill plug first, then prep the differential

   Before you touch the cover, remove the fill plug — if it turns out to be seized, you want to know that before the axle is empty, not after. Jack the truck at the rated points and set it on stands — this job has you working directly under the rear axle, so don't skimp on support. Clean off the exterior of the differential cover with a rag or degreaser before you start pulling bolts; you don't want years of trail dust falling into an open gear housing.

   Jump to 0:00 in the video →
2. 2

   Pull the cover bolts and drain the full sump

   Position the drain pan under the cover, then remove the cover bolts working from the top down, leaving one or two upper bolts loose until the end so the cover doesn't drop unexpectedly. Once the seal breaks, the fluid comes out fast and all at once — this is the main way this method differs from a drain-plug job, so make sure the pan is big enough and well-positioned before you pull the last bolt. Let the cover hang or come off fully and let the housing drain completely.

   Jump to 1:03 in the video →
3. 3

   Clean both mating surfaces thoroughly

   With the cover off, scrape the old gasket material or sealant residue off both the cover and the axle housing using a plastic scraper — metal tools can gouge the sealing surface and create a leak path that no amount of sealant will fix later. Wipe both surfaces down with brake cleaner and let them dry fully before moving on. This is also a good moment to look over the ring gear and carrier for anything that looks obviously wrong — metal shavings in the old fluid or chewed gear teeth are signs worth stopping and investigating further before you button it back up.

   Jump to 2:02 in the video →
4. 4

   Install the new gasket and reinstall the cover

   The cover seals against the housing with a gasket — install a new one rather than reusing the old (the video uses a reusable aftermarket gasket). Only add RTV sealant if your specific gasket or service manual calls for it; it isn't the default here. Position the gasket, set the cover back on the housing, and thread the bolts in by hand first, then tighten in a cross pattern — not a simple circle — to seat the cover evenly, finishing with a torque wrench to your manual's spec. Uneven tightening is the most common cause of a cover that seeps days later.

   Jump to 3:21 in the video →
5. 5

   Reinstall anything you removed to get access

   Bring back any skid plating or brackets you took off for clearance. If your truck has the electronic locking differential, take a moment to check that its wiring harness and connector weren't disturbed or pinched while the cover was off — you don't want a locker fault code from a connector that got knocked loose during the job.

   Jump to 4:11 in the video →
6. 6

   Fill with fresh fluid and check for leaks

   Locate the fill plug on the side of the differential housing and fill with Motorcraft 75W-85 synthetic hypoid gear lubricant through a pump or squeeze bottle, following the level your service manual specifies relative to the fill hole — use the capacity figure below as a cross-check on roughly how much should go in, not as the stopping point on its own. Reinstall the fill plug, torque it to spec, and lower the truck. Take it for a short drive, then recheck the cover and fill plug for any seepage before calling it finished. Pour the old fluid into a sealed container and take it to a recycling center.

   Jump to 4:28 in the video →

Specs

Safety notes

• Never get under a truck supported only by a jack — use rated stands at the correct lift points.
• Let the differential cool before draining if the truck's just been driven; gear oil retains heat longer than engine oil does.
• Fill to the level your service manual specifies relative to the fill hole, using the capacity figure as a cross-check rather than the sole guide.
• Torque the cover bolts and fill plug to the spec in your service manual, in the cross pattern described for the cover, not a simple circular sequence.
• Wear nitrile gloves — gear oil has a stronger, harder-to-wash-off smell than engine oil, and some additives are irritating on bare skin for extended contact.
• Take the drained fluid to a recycling center; never pour it down a drain.