Hi everyone -

1. I have never changed ATF on any car I have owned. But, is it something that ought to be done? I am a very faithful oil changer, but ATF is another thing. I have the ZF transmission (smooth as silk, works fine). And how often should the ATF be changed?

2. How hard is it to change the rear crankshaft seal? What's involved? I am a pretty competent diy-er, but this would be bigger than anything I have taken on so far.

I recently changed the fluid in my AW70 tranny. The Haynes book shows a procedure for changing it underneath the car. I followed the Haynes procedure, however apparently it is easier to disconnect the upper fluid tube at the radiator, connect a hose to the radiator to a fluid collector, then run the car until the fluid spurts or bubbles. Keep adding and removing the fluid until it is clear. It may take about six quarts to clean and replace the old stuff. There might be more details on this in the 700FAQ section.

The conventional wisdom seems to be that ATF doesn't need changing, but cared-for RWD Volvos go way further than conventional cars and can use a fluid change at about the age/mileage you'd be considering scrapping some cars.

I never did it on the 740 (AW71?) and OD the solenoid gummed up and rear bushing failed at 250,000 km. I think a fluid change would have prevented the OD problem and much delayed the bushing problem.

On our 940, I had a flush and fill at 180,000 km despite the fact that nothing appeared wrong. The mechanic said "much crud" including metallic bits came out, and pointed out that those metallic bits can hang up in the solenoid-controlled valves due to the magnetic field. Also, the transmission did actually improve in action over time after the flush and fill.

The ZF may not have a solenoid, so you have one less reason. Even so, I would do it.

ATF swap easy. Read the FAQ. 20-30000 miles or sooner if fluid is brownish and a tad smelly. 100,000 miles plus with synthetic. Yes you should change it....

Rear seal involves tranny removal....and associated driveline dehookage or engine yankage...(which is the way worser way)