Spreadsheet for calcs is now at
http://home.comcast.net/%7Ebrucepick1/brickstuff/FluidChangeRates.xls

It's partially manually-operated.
You need to enter the correct percentage - how much of the total fluid capacity you're changing per cycle. Enter it once and it spits out the results.

And, the percentages to use for p/s and auto tranny fluid for the '89 240 are given so you don't have to do research.

A reader suggested that - for tranny fluid changes - draining the pan first and then adding fresh fluid might give better results than what the calculations show. That's possible; I'm not sure. In any event, its interesting to see what the calcs show, especially in terms of the phenomena of diminishing returns as you add cycles.
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DAMHIK: Don't Ask Me How I Know - - - Sven: '89 245, IPD sways, electric rad. fan conversion, e-codes, 28+ mpg - auto tranny. 500 mi/week commute. '89 245 #2 (wifemobile). '90 244 (spare, runs).