Wltoys 12428b (part 9: lubricating differentials)

I read somewhere that the metal differentials on these cars come a little dry, and it's true.  It's not a big deal to pull out the various screws to be able to access the rear diff and to apply some machine grease.  It's all shown in the exploded parts diagram for the diff and comes apart easily enough: 

Exploded diagrams are goooood.  It's SO nice having a proper car..

Ensure you also lubricate the gears inside the differential, there's another four screws to access those.

Rear diff in carrier, ready for reinstall.

NOTE: When reinstalling Be sure to orient the diff the correct way in the carrier lest your rear wheels will drive in the wrong direction.  I did that .. ;) also note that you align the bearings on the axle with their housings within the diff carrier.  It's pretty straight forward.

Lubricating the front: getting access to the front diff is pretty straight forward.  After removing the body, invert the car and remove the bash plate, front bumper and the long bolts holding on the lower control arms.  After that it all drops away and you can remove the front diff cover:

Note the orientation of the diff, don't put it in backwards!