nauticalx

Manual says MB fluid or Dexron III. Which is the older (non synthetic) fluid.

Newer is the (synthetic) Pentosin CHF 11S.

Not getting a clear answer after searching around. RMeuropean.com shows CHF 11S for the C207.

Q-1-46-0001 Old Non Synthetic/ Dexron III equivalent
Q-1-32-0001 Synthetic Pentosin CHF 11S

Anyone know what the C207 uses? I have a 2010.

BTW, this is not a maintenance item but change your fluid! It looks like brown sludge in there after 40k miles.

nauticalx

no one knows!? dealer says new style CHF 11S is used. However, when asked about manual stating otherwise, they were at a loss for words..

Late

Anyone know the answer to this? Every auto parts store is telling me to buy CHF 11S but the manual does say you can use "approved ATF Fluid"

cmlf1

I have run into the same problem. My 2010 E500 Coupe manual states approved ATF, but most guides state Pentosin CHF 11S

Late

The Cold weather is making the the noise louder. im going to try the chf stuff tonight. ill let you know if it causes any issues short term

Late

Topped it off with the pentosin chf 11s last night ( $30 green tin can) and on a cold start up this morning the grinding noise is gone. The fluid level was barely touching the meter on the cap so i filled it to the max line.

it might just be my mind playing tricks on me but the steering weight also feels a little tighter than before.

I'll report back if there are any issues with leaks etc.. caused by mixing the fluids. So far so good.

oldmots

Just did a modified steering fluid change on my 11 E550 Coupe. I used a full synthetic CHF11S clone by Prestone (Prestone European) which I can get at the local parts store. CHF11S is the right stuff. I suck out the old fluid from the reservoir and measure it, about 4 oz, and refill with the same amount of fresh fluid. I then drive the car around the neighborhood with a few lock to lock turns. I do this process three more times. This gets most of it changed. The old fluid after 40K is definitely dirty brown, not green like the fresh stuff. I have three other European cars and I have done this with them for years, never had a steering problem in many thousands of miles. Steering fluid really should be changed about every 40K or so for long steering rack and pump life. I use Mobil 1 full synthetic ATF for my Jaguars since they specify Dexron III. This probably would work in the E550 as well.

Late

Agreed on the fluid needing a change. the original fluid does have a brown tinge to it now ( 50k miles on my car) and i will be flushing it in the spring time to get it running on fresh stuff again.

I'd Recommend any DIY'ers on here take a look and do some preventative maintenance. Its a super simple Job and something that i am guilty of neglecting on all of my previous vehicles.

ffr2014

Thanks for this info. Will be doing mine soon.

beejAMG

how do you drain the old fluid?

oldmots

Just remove the lowest hose fitting on the rack and let it drain. Refill the system and then you have to bleed it by turning lock to lock with the wheels raised 3 or 4 times to get the bubbles out. I seldom do this since just sucking the fluid out of the reservoir is much simpler. You don't need to really get every drop of the old fluid out since the stuff is synthetic. You could actually let the stuff go for the life of the car, there is no schedule for changing it. I just think that some replacement will lengthen the time for a rack replacement if you are keeping the car forever.

gonein10

The difference between ATF and Pentosin is quite clear, pun intended. ATF is red in color and the Pentosin is clear, light green in color. I don't think mixing the 2 is a good idea

Late

I'm not sure why the manual says to use ATF fluid but i believe the fluid is synthetic from the factory. few months now and no issues have come up with just topping off using the synthetic. hopefully the weather stays nice in the northeast from hear on out so i can do my turkey baster flush.