Ah, I neglected to notice you were across the pond, otherwise I would have directed you to examine beneath the passenger side of the bonnet...

The 124 and 210 chassis estate cars are rather different in this area. The 124 uses a "dual pump" which provides hydraulic pressure for both power steering and self leveling, but uses separate fluids to do so. It contains a typical small reservoir for the power steering fluid and in addition is plumbed to the larger reservoir for the leveling system. A common problem is a failing seal and the pump mixing the two fluids together.

The 210 is simpler, with only the larger reservoir and the same hydraulic fluid powering both steering and suspension.

MB does not specify any change interval for this fluid (neither did they for the 124 suspension). The conventional wisdom on the earlier cars was to change the fluid every 3-4 years. My personal opinion is don't bother, that is overkill. With only 25K miles in four years, just top off the fluid and don't worry about it. Your owners manual should specify the fluid required. Likely it is only available at the main dealer, or from a Mercedes specialist.

- JimY