MERCEDES ABC Fluid / Filter – Service?

So many of the car manufacturers these days are specifying “lifetime” fluids.  An example is the Mercedes ABC (Automatic Body Control) suspension system, which uses normal hydraulic fluid, like power steering fluid.  What is the normal service interval for changing the ABC fluid?  There is NONE…it is lifetime.  Yet, on the other hand, we see LOTS of Mercedes in the shop that have ABC system failures, of several components, and these elements are not cheap to repair or replace.

So, are we to just accept this, or is this just an attempt by the manufacturers to push to the side some of the normal maintenance procedures to help “pretend” that the overall maintenance costs of the car are less, to demonstrate to potential car buyers that the cars are not very expensive to maintain?  We have seen that with BMW / MINI, where they changed the normal oil change service interval from 7.5k / 10k miles, to 15k miles, just because they wanted to show the public that the cost to maintain the BMW over the initial 5 years of ownership was less, only to have it come back and bite them.  In 2013, BMW  and MINI changed their position, and reverted to where the car should have its oil changed every 7.5k / 10k miles.  Is this what Mercedes is doing w the ABC system as well?  How would we know?  How could we find out?  Well….inquiring minds want to know.

So, just like back in high school science class, if you have a hypothesis, you set up a test plan, and set about to see if your hypothesis is proven to be true.  If the hypothesis in this case is the Mercedes ABC system needs to be serviced regularly, rather than run as a “lifetime” fluid, then we need two cars, and two samples, to conduct side by side tests.  Due to the size of the BRracing customer base, this is possible….and, this takes time, years in fact.

We would have one car that has run with the normal ABC system, w no changes, no fluid flushes.  The other car, we would …..put a special filter assembly into the ABC system, and run it, and then perform the ABC fluid changes regularly.

What has the filter got to do w the test?  Part of the reasoning in the hypothesis is that the fluid accumulates particles, and these particles are the reason for the wear in the ABC system, ultimately causing the failures and damage to the ABC system components.  We have also seen this in many of the transmissions that have “lifetime” fluid, like the early BMW and MINI transmissions.  To further prove the point w the ABC system, the filter would have a spherical magnet, in position in the filter to draw away from the flow the particles, rather than just have a filter to try to separate them from the fluid flow.  The filter would also have a serviceable element, to allow us to further clean and purify the system on a regular basis, or constant basis. Finally, the filter would have a “window” to where we could examine the color and state of the fluid all the time, or whenever desired.  We know we have seen the dark, dirty hydraulic fluid, and when you subject that fluid to a magnet, particles can be drawn out of it.

Finally, as part of the test, after the subject test time / mileage, the suspension parts would be dismantled and examined, and determined if any change occurred in the wear, along w the documentation if any change was noted in the failure rates of the parts.  While the test sample is small, the test results could prove the hypothesis none the less.


We indeed found, very quickly, that the hydraulic fluid indeed captured metal particles. We could see the area around the magnet capture and hold the metal particles.  We could also see that the fluid color was staying clearer than the other test vehicle (w no filter, and no fluid changes).  Finally, over a long period of time, we pulled the suspension elements of the ABC system (shocks, pump, solenoids) and compared the two.  The results are clear, the system w the filter and fluid changes were in dramatically better condition, and had no failures, while the baseline car had wear, and had ABC suspension failures.

Its simple….we need to service all fluids…there does not appear to be a case of “lifetime” fluids, at least not relative to the ABC Mercedes suspension system.

Don’t neglect your car, ensure it gets the service it needs….you can pay now, or pay much more later.

BRracing – providing better care for our customers cars