Automatic transmission fluid level question

I mentioned this in my rambling Saab-to-Volvo thread, but I figured I'd post it separately to get a few more knowledgeable eyes on it. The car in question is a 2006 Volvo V50 T5 AWD, equipped with the AW55-50 5-speed automatic.

I did a drain-and-fill on the transmission this afternoon. Here's what I posted in the other thread:

I measured the drained fluid and took exactly 4 quarts out - again, the fluid looked old but not burned up, and smelled like trans fluid. I refilled with the Aisin OE fluid through the stupidest dipstick arrangement ever (seriously, I know space is tight, but one should not have to start removing the dipstick from underneath the car), put the car back on the ground, and went for a ~15 minute drive to warm everything up. When I got back it was basically dark, but I still wanted to confirm the fluid level in the trans. I checked it a few times, and best I can tell (it's really hard to accurately read a dipstick you have to remove sideways in the dark) it's reading ever so slightly over the HOT mark. I've always heard not to overfill automatic transmissions, but never understood why and I haven't had one in 15 years, so I don't know how serious a couple millimeters over the marks really is. Do I need to get under there and drain out the excess? Shifting was absolutely fine before the fluid change, and felt even better with the new fluid in there.

I'm completely ignorant when it comes to automatic transmissions. Assuming my reading of the level is correct (I'm given to understand the range between the marks corresponds to quite a small amount of fluid), how critical is it to get right on the marks? Is a little bit of extra fluid going to lunch the trans in short order, or is it inconsequential unless you're talking about significant amounts of fluid?

On an AW55 it's not going to hurt much to be a little over as long as we're not talking quarts overfull.  I know on the TF80 (the AW55's big brother) it is recommended to fill to the check plug level, then add an additional half quart to prevent fluid starvation in hard cornering.  I've done this for the past 90k miles or so with no issue.

Hmm.  Probably due to change the fluid.

And if you think the dipstick is a pain in that car, you should see that trans in a GM cute ute. (Torrent?)  You have to either have tentacles instead of fingers or you have to unbolt the engine mount, because the mount bracket encases the dipstick on all sides.

In reply to Pete. (l33t FS) :

Thanks for the clarification. It's definitely not overfilled by much, and I don't know that it's really overfilled at all, but again, my ignorance is the real issue here. I only realized after the fact that I failed to change the Magnefine filter that a PO put in one of the cooler lines, so I may end up dropping a bit of fluid out when I go back in to change that out. I really just want to get all the under-the-car stuff done before it drops below freezing. Out of curiosity, how often do you change the trans fluid on yours?

I really don't understand why trans dipsticks are made so inaccessible on some modern cars. The one on the Volvo could simply have a longer tube wrapping up around the airbox and it would be easy. It's inexplicable, unless they just don't want people checking the fluid.

Oh, and I forgot to mention in the other thread that I did find evidence of someone working on the rear diff at some point: there was a Craftsman 15mm combination wrench hanging from the top of one of the diff mount bolts.

...they don't want people checking the fluid.  Might put the wrong stuff in donchaknow.  Toyota has an FU clip on the dipstick, Nissan bolts the dipstick in place...  actually now that I think of it, I think the US-GM implementation of the AW55 also bolts the dipstick in.  Have never seen an SAAB with the AW55 so I am curious if you can just pull it, like Volvo, or if it bolts in like GM.

It was a very popular transmission in the 00s   The list of vehicles it was used in is long and diverse.

Dexron VI works just fine in Aisin-Warner automatics instead of the expensive Toyota stuff, but that isn't to say that someone might throw some Type F or 7176 or God knows what in there.

Pete. (l33t FS) said:

Have never seen an SAAB with the AW55 so I am curious if you can just pull it, like Volvo, or if it bolts in like GM.

 

our 2010 9-3 2.0T has an Aisin automatic with the shortest dipstick ever, bolted in place.  makes me want to punch a baby.

In reply to AngryCorvair (Forum Supporter) :

So GM style then 

I've never had one being slightly overfilled to be a problem.

Here's a good one. The Bentley has a Turbo 400. The dipstick is mounted under the windshield wiper assembly. To check it you first remove the wiper fuse, then remove the cover over the wiper assembly, then stick your arm down through the wiper linkages to feel for the dipstick, which is mounted just beneath the cruise control servo. I almost need another joint between my elbow and wrist to reach it and the wiper linkage is probably strong enough to steer a truck so you know if they turn on, you will be pulling back a stump.

Oh, and the actual first step is to drape the fender with a protector because you can't get to it without leaning on the fender and you wouldn't want to scratch it. 

I was and remain curious about the inner workings of these things, so I did a little more searching and came up with this page from Transmission Digest on all the little differences between manufacturers that use the AW55-50. It's not exactly what I was looking for, but it's fascinating to me as someone who has been driving manuals exclusively for many years. I had no idea there were so many modes and parameters involved in something as simple as shifting gears.

My '04 Saab 9-3 with the auto has the AT dipstick bolted in. It's actually easier to get at from underneath the car.