Yes, MB oil is "mineral based." If you are knowledgable in hydraulics it could be possible to find a "cheap" alternitive to the $16 the stealership, ahem, dealership charges per liter. You would be taking a calculated risk of something being not properly lubed, seals being eaten/swolen, or metal parts corroding.

Because of this, I don't put anything non-MB approved in my suspension, plop down the cash and get the real stuff.