Guide 2016~2021 CX-9 DIY Transfer Case + Rear Differential Fluid Drain and Fill

Dumb question here, but for the transfer case do you fill it until fluid comes out the fill hole or is there some other procedure for determining the proper fluid level? Reason I ask is I filled it until it leaked out but the axle seal is lower than the fill hole and I'd hate to put too much in and cause that axle seal to leak. If anyone can let me know so I can drain as needed I'd appreciate it. I can't find any info anywhere else on the subject.

Edit: I see 2 posts above says it should be filled to the top but want to confirm 100% you are talking about the transfer case too. Replacing that seal will be a b***h if it pukes.
Yea, I am not convinced on filling the diff to the fill hole. Exact same known issue on Chevy 1/2 ton diffs. 2002 is mine for example. The fill hole is above the pinion seal and if you fill it to the hole it increases the chance of puking that seal. Seal is happy holding back splash oil, but not oil 24/7/365. Book says 5/8" to 1-5/8" inch below the hole. I do 3/4 which is a perfect 2.0 qts. To the hole is 2.5-2.8 qts. If your saying the fill hole is above the axle seals then I might stop at .5 ish and just do more often. 16oz is a pathetic amt of oil for a diff though, wow
 
Rule #1 for draining any gear box....loosen the fill plug before your remove the drain plug. If the fill plug is stuck and you can't get the fill plug out, don't drain the oil out.

Red Line 75W85 is my choice of gear oil for these jobs. I use the recommended amounts.

The plugs need good gaskets on them. Possible for a sealant would be plumber's thread sealant paste...it doesn't harden and it seals liquids. Teflon tape isn't a good choice...some of the tape remains on the internal threads the next time you the do the change, and shreds of the tape could be pushed into the machinery when the plug is reinstalled next time.
 
Does the 2016+ CX-9’s have one or two differentials? I assumed that since mine is AWD, it has both a front and rear differential.
 
Does the 2016+ CX-9’s have one or two differentials? I assumed that since mine is AWD, it has both a front and rear differential.
If you read through the previous posts in this thread, there's two places where oil is changed, the rear differential in the middle of the rear wheels, and the "transfer case" in the front.

The "second differential" is actually inside the transmission or something like that which you don't have to worry about. It's the transfer case in front and the rear differential in back that need oil servicing.
 
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