I had the car recently inspected, esp. for what I believed to be a tranny fluid leak. Reason being, I find minor residue of leaked fluid under the central area of the car, only once it sat there for 2-3 weeks.
Mechanic says he can't see anything, where it possibly could leak from and tranny fluid level is where it is supposed to be.

He noted the SLS fluid level to be low. I found the part # for the Febi ZH-M hydraulic fluid in another thread. Thank you.
I'll be getting 1 Liter of it to top of the reservoir. I am reading the W124 SLS does not use the same fluid as in the PS system.

First and foremost, I'm trying to find out what is leaking while the car is parked for a few days. Could that be SLS fluid I find under the car in the proximity of the transmission?
Ps, suspension is great, very smooth ride. The air accumulators have been replaced a few years ago.

The SLS fluid is clean, pretty thin and feels like brake fluid.
I'm going through a bit of this myself with my 1999 E320 wagon. Different fluid, but all same principle. Be careful with where this fluid is leaking, as it attracts water and can hold water, road salt, et. al, and eventually cause heavy rust in your rear suspension.
If you are seeing a leak of fluid near the area of the transmission, check the hard lines under the car, particularly at the spots where the brackets with rubber grommets hold the lines to the bottom of the car.

Phil Forrest

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1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson

Catch some of the fluid in a clean aluminum tray and show it to your tech if you don't recognize it. ATF leaks are common after sitting for a few days as the torque converter drains back into the transmission and the fluid level rises in the transmission pan. If it only leaks after a few days and it is ATF and it is slightly to the right side of the car off-center, look at the two piston covers just above the pan gasket.

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Thank you Gentlemen.
The car never did anything like this. There's got to be a place it comes out.
It's not much, in fact it's minimal. The original spot size is not more than a Quarter, but than the dry concrete absorbs it to about the size of an average hand.
All this happens while the car is sitting for approx. 2-3 weeks, as I already stated.
I'll keep monitoring the situation.