My rear cover leaked slowly when brand new.
Warranty sloppy silicone seal repair. (Messy job but usually is leak proof.) They left a bracket off for a wire, so that was put back on next oil change (why should I do it?).
Leaks again around a left lower bolt which probably threads into the carrier void... same bolt meets a bump with a drain plug in it. Needs silicone on the bolt with clean threads probably. They can warranty that next oil change...
That one way to keep the fluid fresh (unless they dump it back in, I'll have to watch next time).