Just bought a 1998 V90. Owner's manual says to flush/change auto. transmission fluid every 30k miles (no exceptions provided). But a PDF file I found online states as follows (this is specific to the Volvo V90):

The oil should be changed only in the following instances:

A When the diagnostics system has registered oil temperature too high, (diagnostic trouble code (DTC) 2–3–5).

B The oil smells burnt and is discolored but no diagnostic trouble code (DTC) has been recorded, for example, in connection with heavy, concentrated use.

C On cars used in continuous taxi service and or used to haul a trailer or caravan for most of its mileage, the oil should be changed at a service interval of 75 000 km.

Which is it: every 30K miles without exception, or as needed per A/B/C above?

And how much labor should I expect an experienced independent Volvo mechanic to bill for this job -- less than one hour? (Cost of parts would be about $80 for 8 quarts, right?)

 

I only know of one transmission that requires a regular oil change (My VW's DSG requires it at 40,000 intervals)... Both my 850 and S40 have the same notations about continuous usage/towing or high oil temp faults. You have the AW40 transmission, same as the 960s which note to check the fluid level every 10K miles but nothing about servicing in the first 60K (you need to use the maintance book to see after that).

With that said, I did mine at 100K miles with some DIYers suggest 50K. As to the cost, there's two options, a drain/fill (easy but each drain only gets half the fluid so you need to repeat) but this option is popular with DIYers. The flush requires opening the oil cooler line and watching the color. I got a recent quote of $300 for a proper flush of my S40 - labor plus fluid so that sounds like 1 1/2 to 2 hours labor total.

Here's the procedure clipped from Volvotips.com:

DRAINING & REFILLING
Remove drain plug and drain transmission. Disconnect filler tube and remove oil pan.
Remove and clean oil strainer. Install strainer. Tighten strainer bolts to 18-25 INCH lbs. (2-3 N.m). Install oil pan with new gasket. Tighten bolts to 42 INCH lbs. (5 N.m). Tighten filler tube to 65 ft. lbs. (88 N.m).
To flush oil cooler, disconnect fluid return pipe from transmission. Place end of pipe in container. Add about 3.5 qts. (3. 4L) of fluid in transmission.
Start engine and let idle. Turn off engine when clean oil
comes out of pipe. Connect pipe and fill transmission.


Read more: Volvo 960 automatic transmission service manual