[montr]

Originally Posted by muniz_ri

I did the change in my old e46 and plan to also do it myself in my F30. Did you use OEM fluid or something else? Which transfer pump did you use for the refill?

Here is what I did when I changed the transmission oil in my E90.
I do have a transfer pump but I did not want to be under the car to pump the oil up in the tranny. Instead, I went to Home Depot and got some flexible tubing to fit my funnel. I put the funnel up in the engine compartment and routed the tubing into the transmission filling hole. This was a cheap, easy and effective way to fill the transmission.

[muniz_ri]

Originally Posted by montr

Here is what I did when I changed the transmission oil in my E90.
I do have a transfer pump but I did not want to be under the car to pump the oil up in the tranny. Instead, I went to Home Depot and got some flexible tubing to fit my funnel. I put the funnel up in the engine compartment and routed the tubing into the transmission filling hole. This was a cheap, easy and effective way to fill the transmission.

Very cool!

[ashenfie]

Originally Posted by catskillclimber

info on oil cooler thermostatic bypass and its effect on oil level.
https://www.import-car.com/zf-8hp-tr...n-replacement/

Yes that makes sense, I have done the ZF procedure and it's not that difficult, so I'm not sure why anyone would not follow it.

It makes sense to work on a cold engine and then go though the gears and lastly warming up to trigger the thermostat to open.

[Polo08816]

Originally Posted by ashenfie

Yes that makes sense, I have done the ZF procedure and it's not that difficult, so I'm not sure why anyone would not follow it.

It makes sense to work on a cold engine and then go though the gears and lastly warming up to trigger the thermostat to open.

I think some people are rushing through the procedure. Especially if it requires a cooldown from operating temps to near-ambient temperature. This is why I prefer to do this procedure during the winter where you can cool the transmission down faster with ambient temperatures. Otherwise, you'll have to leave the car overnight.

Originally Posted by catskillclimber

I've done this fluid change twice now and have found temp to be a material factor in getting the correct level but I don't believe it is due to fluid expansion.
My first change was back in 2015 and there was a dearth of info on fluid changed in the the 8HP45. I did come across a ZF procedure in an Audi forum, see attached. I confirmed with ZF that it was applicable to the 8HP45.
I drained the fluid almost immediately after 30miles of highway driving, so scalding hot. Went about adding fluid but was only able to get in ~3.5qts using the procedure. I hadn't measured what came out but it seemed light for the refill. Took it out for a 20mile highway drive and let it sit over night. Next morning went through the procedure again and had to add another qt to get the level right. I was taking the car in for warranty work and had the dealer verify the level, nothing added or drained.
Fast forward to a few days ago and the 2nd change. Drained while hot again and measured what came out this time. Figured I would just put back in the same amount and at least be very close. The transmission case was still warm but I could hold my hand on it so figured it was cooled down enough. I use a barbed fitting in place of the fill plug and snake a hose up to the top of the engine to fill. In went the same amount the came out. Went through the procedure and expected minimal spillage when taking the fitting out. I pulled the hose of the barb and I did get a "firehose" of fluid. Got it plugged up quickly and decided to let it sit for a few more hours. 2nd go around I got the same result. Since I had a barbed fitting in the fill hole the drain out of the bard sits higher that when draining out of the hole. I remeasured what came out and got the same volume. Let it sit overnight like the 1st change and the level came right in following the procedure with no fluid +/-.
The Audi procedure mentions thermostatic control valve in some units that require exactly what I did to get the level right.
My best and only guess at this point is the cooler drains out with the rest of the fluid but is bypassed befoer the fill and first level check. The test drive opens the cooler circuit up resulting in a lower level initially on the next day check.
If anybody has another explanation.....

Originally Posted by catskillclimber

info on oil cooler thermostatic bypass and its effect on oil level.
https://www.import-car.com/zf-8hp-tr...n-replacement/

I agree with catskillclimber on the thermostatic bypass accounting for the extra volume. As a sanity check, I would prefer to measure the volume of fluid drained just to get an idea of how much to fill.

My belief is that it is far more harmful for the transmission to be low on ATF than for you to overfill it by a small amount.

[AtlantaDan]

Originally Posted by Polo08816

I think some people are rushing through the procedure. Especially if it requires a cooldown from operating temps to near-ambient temperature.

It does not require a cooldown. You just have to get the trans fluid up to a certain temp, which is between 86-104 degrees.