Dealer says my Infinity M35X should have the rear differential purged? on 2008 Infiniti M35

I have never heard of this before in 52 years of owning automobiles including Cadillacs, etc?
The car has 48,000 miles.

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1 answer 1 comment
According to the Alldata information there is not a manufacture recommended interval for the rear differential. Most likely the vehicle came factory filled with synthetic gear lube and is considered lifetime. we recommend gear lube drain/replenish on time and mileage 60k would be a interval that I would be thinking about changing gear lubes.
Dan @ Waterloo Motors Inc.
THANK YOU.
IT'S MUCH LIKE I THOUGHT IT WOULD BE.

MALCOLM