I'm not sure what to make of this. I completely flushed my tranny fluid a couple of weeks ago using the oil cooler-return line on the radiator and a 3/8 tubing. I simultaneously refilled the tranny using a tube and funnel in the dipstick tube. I had to shut the car down several times in order to allow the fill rate to catch up to the drain rate. I flushed all 9 quarts (plus some new) out of the car and had it entirely refilled in an hour or so. I later installed a 5/16 magnafine filter on the return line. The tranny runs fine. No real problems and shift seems a little softer now (but kickdown cable still needs adjustment).

The issue is that when I start it up in the morning, or after it's been sitting, the tranny makes this "whirring" noise when I drive. It seems to go away after the whole car and engine has reached normal temperature. It sounds akin to the sound a manual transmission makes in fast reverse. I did not use Mobil1 (too expensive) but used a valvoline durablend ATF that was a bit cheaper than the Mobil but certainly not a mickey-mouse cheapo fluid.

I've put several hundred miles on the car since I flushed it and it's been fine, but this noise bothers me. It wasn't there before I flushed the old burnt fluid. Now it is. Is this a real problem, or just a side effect from using the Valvoline ATF?

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Volvo #6: all wagons.... 1972 145S, 1976 245 DL, 1983 245 GL, 1986 740 GLE, 1990 740 GL, now a 1995 940...