I am pretty much in the same boat, want to use the synthetic, although I'd pick Amsoil over the M1, just because I used it before and now and it does work better in my opinion. Unfortunately I did not (nor do I now) have a whole lot of time to do the research on fluids. I did cal Exon though and asked them point blank will Mobil 1 work in my S60? They never gave me a straight answer, just that if Volvo says it's ok, than by all means. I did not call Volvo because I am positive they will tell me this "Use Volvo approved ATF from our beloved dealership chain". I already ordered a case of 3309, so I have no problems using that stuff, doubtful if it's any better or equal to the Amsoil.
If the transmission is built by Aisin with same seals specs as the Toyota, then it will be fine using the Amsoil because that's what I am been using in my son's Camry for the last 5 years and probably 65k.
& no this is not an attempt to restart "transmission fluid" thread

 

FWIW, tons of posts say Toyota IV is the same as JWS 3309 for a fraction of the cost of Volvo fluid I am running the M1 and the transmission does act differently, whether it is a bad thing or not, I hope I do not find out lol.

No need to rehash the thread, we all should know that the fluid should be JWS 3309 or compatible.

 

I have about 1200 miles on it since the flush/change, went to Orlando and back LOTS of HIGH highway speed and LOTS of stop and go traffic. So far, no problems, but I didnt have any issues with it befor, and the fluid didnt look that dark befor. the wife says she can feel a differance (better shifting) but it never has been my every day driver so I dont know.
I still have myself convinced synthetic is better. AND I can get it right down the street.

 

If you don't mind been a "Guiney pig" for all of us wondering what to use, please keep updating this post as you put more miles. Or maybe moderator wants to make it into another sticky idono, but sure would be nice to hear how it behaves. Does anyone know if there is such a thing as ATF analysis as there are for the engine oil, I guess I could google it, but that requires opening another tab and I think I am maxed out

 

After 6k+ on M1 providing my indy did indeed swap out the fluid

I have firmer shifting, this one is a little tricky because I also had a completely busted upper engine mount replaced at the same time... so it is the ATF or the mount...

Another thing I noticed is the tranny, when cold, seems to downshift a little sooner than I would like, not bad but you can notice the rpm's spike a tad, does not cause the car to surge or anything it is just noticeable.

However, the above is almost completely gone once the ATF warms up, I read that the tranny has oil temp sensors and what not and does some stuff depending on the temperature of the oil. So could the above be because of syn vs regular oil and the temps?

Overall I am happy I had the flush done, wish I did not wait till 72k as it was pretty dark... not burnt smelling though. Only time will tell if any issues arise.

 

I just purchased a 2001 s60 non turbo 5speed auto with 80k miles. The car has no manuals with it and while I was doing some basic maintenance started searching the volvoforum for some answers I dont see anywhere my question.
Do I check the tranny fluid level with car running or with engine off?

 

I am still happy with putting the Mobil 1 in mine, have around 5 thousand miles on it and no problems, getting into cold weather here now and so far, no issues at all.
Still havnt put in in the 2002 S60 yet, the last time he came home with it I got to replace the hood latch cable, (that was fun). He will be back Wendsday, maybe over the Christmas break I will get it done, if it warms up.

 

Thanks for the info.

 

10k on M1, no major issues so far, only the minor ones I outlined in an earlier post.