My 2000 OBW has 110K. What is the recommended service interval for the front and rear differential fluid change?

owners manual is always an excellent reference for stuff like this, which varies with usage. if you don't have one you can usually post in the parts wanted forum or look on ebay and get them for chump change.

 

auto or manual trans? 1 of the gear oil bottles is enough to fill to capacity, and at 110,000 miles i'd probably change it.

you can also look at the bottom left of this screen right now and see other similar threads to yours. there are 5 other differential threads there. check those out and/or check out the search gizmo.

Its an automatic. Reason I posed the question is because my owner's manual simply says to 'inspect' every 30K, but unless the vehicle sees 'severe driving conditions' there is no recommended replacement interval.

gotcha, there are tons of high mileage subaru's with the original gear oil in it. they can easily get by with never changing. 100k is a great mileage to consider changing it, i would. i'd bump to a high quality synthetic.

Sounds like you got your answer, though IMO a diff fluid change in the first 5 - 10,000 miles of its life is very wise and helps achieve 'lifetime' fluid fill. I'll often change every 30,000 miles but it depends a bunch on my usage in the vehicle in question.