My 1999 S70 takes 3.5 quarts when I drain via the drain plug. Done at the same time as an oil change, just move the collection pan over, and fill through dipstick.

I could never figure out how to get the transmission hose off the radiator.

There is a better way to flush all of your tranny fluid without jacking up the car and making a mess. Of course, it will take at least 12 quarts of Mobile 3309 ATF and 3 empty gallon containers.
The transmission cooler is in the radiator, and on the driver's side are 2 hoses that serve the cooler. The upper hose is the output hose. Just unplug it from the radiator, attach a clear hose to extend to the gallon jug, marked at the 2 quart line and start the car. When 2 quarts have pumped out, turn the car off, add two quarts to the tranny through the dipstick hole, and repeat the process until you have gone through all 12 quarts.
Total time to do this is about 30 minutes. Remove the air intake hose from the radiator to the air cleaner box for easier access to the dipstick.

Klaus
--
1975 164 w/174,800mi (Sold) 1995 850T w/91,000mi, 1998 V70R w/129,000mi

Hi Andrew,

Assuming you are talking about an automatic transmission, you are in the ballpark. I usually add 3 and start checking. It will usually end up taking 4 or so, but you don't want to overfill at first. Also, 1999 FWD models should have the AW55 5-speed automatic, which takes different fluid (available from Volvo).

Hope this helps,

Joe S. - Volvo Master Technician

2000 S70 AWD, 1995 850 Turbo, 1981 242 Turbo w/intercooler