Front diff oil change frequency and CV axle disconnect

People seem to change both front and rear diff oil at the same time, and the suggested interval is 30k.

Is the front diff oil change needed as often as the back if you rarely use 4-wheel drive? Or is there stuff spinning in the front diff all the time that wears the oil?

I did notice that when I spin the front wheels, the front CV axles spin all the time when in 2WD -- is this expected?

I grew up in the era when 4x4 trucks had manual lock-out hubs, so somehow thought "automatic hubs" disconnected at the hub.

On a 4R, are the hubs ever disconnected from the CV axles, or is the only disconnect in the differential?

 

What's the manual say? Go by that.

 

The front diff spider gears are turning in 2wd since the driver side is always connected to it. Some say the passenger side shaft before the ADD is spinning in the opposite direction. I just change it at the same time as the rear and transfer case since I'm already there.

 

Manual says the diff oil must be changed immediately after each water crossing off-road. Later year manuals also state water crossings can result in death.

 

Here’s a dandy video.



It refers to a Tundra, but it’s almost exactly the same as a 4Runner.

 

I changed the rear diff fluid at 1000 kilometers. I seldom use 4WD other than for a few kilometers once a month for lubrication and functionality purposes. The few times I use 4WD in the winter are insignificant AFAIC. I intend to do the transfer case and both diffs at 48,000 kilometers in conjunction with an oil and filter change. This is the routine I used on my three previous 4Runners.