My 2001 S80 normally drives fine. But every week or two I will have a series of transmission "slips" and then it goes away. I think it only happens in 3rd gear. Most the time I cannot repeat the slipping. Any ideas what the problem might be?

An independent shop took look at it and they didn't find any problems. The transmission fluid level seems a little high to me and has a slight brown tint to it.

 

Does the fluid smell a little bit burnt? Just after I bought my 2002 S80 T6 with 150K on it I talked to the guys in the service dept at the Volvo dealer where it had been regularly serviced. When I asked about changing the tranny fluids, they advised leaving it alone. Wish I had listened. Perhaps it was due to fail at 161K anyway, but there eventually was no way around a complete rebuild. Cost ~$3,300 at AAMCO.

 

I got the advice a little late. The car threw a transmission code (p0842) and I figured I had nothing to lose so I changed the transmission fluid, but did not flush. I Just drained what would come out and replaced with new. The old stuff looked pretty bad (see pic).

So far the transmission has not slipped at all and shifts are softer than I ever remember. I haven't gotten any codes either. We shall see how long it lasts. I had planned on doing another drain and fill cycle but might hold off now. I don't want to shock it too hard.

 

Sounds promising, I hope it keeps going. You'll know it's going on the blink if your tranny fluid starts to stink. That's because when it starts slipping the fluid gets very hot.