80W90 in transfer case and GL5 75W90 in rear diff, or use GL5 75W90 in both?

[KGMtech]

My hyper maintained 2019 QX60 will need the transfer case and rear differential fluid changed in 3k kilometers, I currently have 80W90 in the transfer case and a semi-synthetic GL5 75W90 in the rear differential. Can I standardize these 2 oils with just using the GL5 75W90 for both the transfer case and rear diff?

I do this service every 35k kilometres - which works out to 2 years. The transfer case only holds 300ml and the rear diff about 500ml, so having 1 bottle of each different oil is sort of annoying.

Would you do it?

 

[Kira]

I'd start by conquering any annoyance caused by two small bottles over one (ha-ha).
Seriously, while the two fluids may be very close in character, I'd verify what was called for by the manufacturer and learn if there are any caveats, such as ,"no synthetics in the rear diff".

 

[slacktide_bitog]

I'd do it

You can use 75w90 in both with no problem

 

[V70tdi]

If your transfercase has brass, bronze bushings or other yellow metal parts in it and calls for a GL4 i would not use a GL5 oil when it can be bad for yellow metal parts. So take a look in the manual what type of oil the transfercase calls for. Some oils are specified to GL4/5 that should be ok to use.
I hope you use the word yellow metal for brass, bronze and other yellow coloured metal alloy. I just translate the word from Swedish if not i hope you get what i try to say