I read on here and seen it mentioned in my service manual that our W108s use Dexon II ATF rather than power steering fluid. I checked my fluid yesterday after (a) needing to use a bit more force to turn the wheels and (b) hearing some slight squeaking when when the wheels were completely turned in one direction. (I have greased the chassis and still hear a slight squeak/groan).

The fluid appeared to be very clean but was a light golden color rather than the reddish ATF fluid that I am accustomed to. The fluid has not been changed to my knowledge in the year I have owned the car (unless my mechanic did so without my knowledge).

I assume the gold-ish color fluid is power steering fluid? Do I need to replace this fluid with ATF? Any other thoughts on the squeak and the need to use additional force to turn the wheels?

Thanks,
CNM

The squeak is most likely to be steering linkage part such as tie rod ends or the drag link.

My 108 almost always made a groan on full lock. This was worse/louder on colder days.

As for PS vs ATF... A LOT of manufactures are going back to using ATF instead of PS in their vehicles. This started back up ~10 years ago and is still going. Most Chrysler vehicles for example (if not all) are back to ATF +4 as the recommended fluid vs plain jane PS fluid. Don't ask me if it's due to the viscosity, friction enhancers, longevity of components, or something else - but I replaced my 300M's contents with ATF +4 per their TSB when I had to replace the pump and it's quieter and smoother now. I would not be surprised if newer MBs used ATF as well. I had ATF in my 108, I tried PS fluid; the steering felt rougher and was louder with PS fluid than ATF.

Your mileage may vary of course... but ATF was also cheaper and easier to find, and both of my systems had some leaks, so ATF was also far more economical - carrying 1 bottle of ATF for trans & steering vs 1 of each with me.

__________________
Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

You might also change your PS filter. It is a donut looking thing and can be purchased through the Pelican Parts Mercedes parts site.

I could never get the whole AFT vs. PS thing down so I just picked up a liter from the dealer. Not cheap, but then the difference in price was only about $10 so it is not like I am going to be missing any meals in order to go with what Mercedes recommends.

But change the filter. It will make a difference if it is clogged.