So, just when does your owner's manual say that tranny fluid should be flushed? I'm also wondering if synthetic fluid might help this matter, because synthetics have more uniform viscosity throughout a wider temperature range than non-synths.

One poster in this thread aluded to harsh shifting. My old '89 740 used to have such a problem until I flushed the tranny fluid. As I recall, the service interval was about 30k miles for the fluid change, and I had let it go to nearly 50k. When I sold that car, at about 150k miles, the tranny felt great -- much better than before the fluid flush.

Some of you folks might do well to look into the claims about synthetic transmission fluids before you do this service. My expectation is that it will substantially reduce the delayed upshifting and harshness problems that many of you are describing.

BTW, the flushing technique on my 740 involved draining the fluid and actually running the car with one of the fluid hoses disconnected. The specifics are detailed in most service manuals. I mention this because a simple "drain and fill" will not replace the fluid that is in your torque converter and transmission oil cooler. That could leave as much as 1/2 of the old fluid in the system. Just don't expect that your corner "Lube-It-All" will do this job right. Try a dealer or Volvo specialist.