I just got my oil changed on my 09 g37 coupe with 120000 miles and the technician told me he was unable to check the rear differential plug was Seized and cannot be checked due to it being too tight. Is there something I should be concerned about immediately there is no leaking or issues with the back at all

Edit: Title clarified.

 

Rear end oil should be changed periodically. I did mine every 20K miles. IIRC, the fitting is the male portion of a 3/8" ratchet. Never used a torque wrench on it, but tightened it to the about the same torque as I do an oil drain plug (~30 ft lb).

Tech probably doesn't want to take on the responsibility should something break. Is there lots of corrosion build up around it?

I'm guessing the drain plug is just as tight. With the car level on the lift, normal filling procedure is to fill until it starts to drip out. Allow excess to drip then reinstall fill plug.

 

I'm guessing u went to some quick lube place? If u go to an actual mechanic shop, regardless of it being "seized" there are ways of getting it out. Most quick lube places or otherwise crappy mechanic places will pass on it because they don't want the responsibility if something goes wrong. If you don't want to do it yourself, check around, someone will do it for you. For future reference, if u end up ever doing it yourself, always make sure to get the fill plug loose before the drain!

 

Are you wanting it flushed? If you’re concerned about the level only there’s no need to worry if you don’t see any leaks. I’ve never checked mine, and don’t intend to unless I need to change something…