Year: 2009
Model: SL63
Mileage: 36K

Servicing the transmission and I went with the filter/pan upgrade kit from FCP Euro. My original intention was the Weistec pan but it was out of stock at the time of ordering and the FCP kit seemed like a viable alternative to accomplish the same goal. It consists of an upgraded filter and a deeper pan used in the G63.

Sequence of Events:

1. Lifted the car and drained the fluid, noting that around 4L of old fluid came out. Using a Schwaben fluid fill tool with a 722.9 attachment, I was only able to get 2L back in cold and maybe another .5L back in at the instructed fill temperature of 45C. I lowered the car and drove around the block to circulate the fluid a bit before the second stage of cycling the old fluid out. No errors, no odd noises, etc. but the car felt a little "off" to me.

Inconsistency Noted

• Frankly, this didn't sit right for a few reasons. Every guide, instructional video and even the Mercedes WIS I purchased states that 4L should go back in cold. This is double what I managed and that is with the standard shallower pan. I recall the overflow level in the kit (green) being noticeably shorter than the original on in my car (off white) which I found strange, since that would offset the increased capacity of the pan. Because of this, I decided to go beyond the drain/fill approach for the next round of cycling fluid out and dropped the pan again to swap the overflow level back to the taller original.

2. With the taller overflow level installed into the G63 pan, I was able to easily pump in 3L of fluid cold. At a temperature of 45C, it accepted maybe another 250-300ml of fluid, which is still off the 4L mark that came out. I raised the temperature to 50-55C and the transmission accepted another 700-750ml easily. It could have taken more but at this stage, I just wanted to balance what went in vs. what came out.

Impressions

• I went for a road test, observing the transmission's behavior in everything from Comfort to full Manual. The car drove beautifully with buttery smooth shift quality. In Manual mode, up-shifts and downshifts were executed smoothly without any hesitation.

At this stage, I am trying to figure out what caused the above behavior and which steps (if any) to take next.

Some Givens:

• The G63 pan is in fact deeper than the original one.
• The transmission temp reading was accurate (verified by iCarsoft via OBD2 and an IR temp gun pan reading).

The only other thing I can think of is the vehicle level being slightly off. I used a QuickJack to lift the vehicle, but taking into the consideration the mechanism used for setting the level, I could see how even a slight pitch could compromise things.

Would appreciate some other perspectives on this. Thank you!

The length of the overflow tube has nothing to do with how much fluid you can pump into the transmission when cold. The transmissions hold the same quantity regardless. If you overfill it, you will get fluid spilling out of the top "emergency" overflow valve.

Hmm...I think a disconnect here is that I should not have tried to measure cold fill (I'm used to servicing ZF and GM transmissions where this is a factor) and just pumped in a higher volume of fluid to begin with, leaving the tool connected until at the 45C final fill temperature.

Still though, shouldn't the net volume be the same (catch up the difference once at fill temperature)? Comparing what the WIS states about a 722.9 service on the G63 vs. the SL63, it should have accepted an extra 2L of fluid.

Something about the level of vehicle being slightly off is sticking with me. Will need to recheck that.

Yes, that is how you do. You overfill by half to one quart when cold, then open the drain when it reaches the proper temp (113F). It should pour out at first, and then suddenly switch to a slow drip. THat's the point where the volume is correct and you close the drain.

Thank you for the sanity check.

I reached out to FCP Euro and they responded that the pan upgrade is mainly intended for the upgraded filter. Apparently, it only accommodates "300-750ml of extra fluid capacity" for the 722.9. I would have appreciated the transparency up-front...but live & learn.