Hi everyone,

I wanted to share something I’ve been observing and using on my 2014 S212 E63S (230,000 km, fully MB‑maintained, stock, always on MB‑recommended oil). This isn’t meant as a technical recommendation or a claim of what’s “safe” or “unsafe” for the engine—just my personal experience and the logic behind it.

Why I Started Looking Into This

I’m not qualified to say whether unplugging or disabling the oil solenoid is harmful. What I do know is that with the high torque of the M157, the engine rarely climbs past ~3,000 rpm in normal driving. And as many of you know, the oil solenoid only opens fully above that threshold, which means full lubrication isn’t triggered often during gentle daily driving.

After reviewing several Xentry logs, one thing became very clear: During engine braking, the solenoid is consistently commanded open, regardless of rpm.

That got me thinking—how can I safely and consistently trigger engine braking using only factory functions?

How to Manually Trigger the Solenoid (Using Only Stock Features)

In C, S, or S+ automatic mode, you can:

1. Pull and hold the left paddle
   
2. The car will automatically select the most appropriate gear for engine braking—usually 3rd gear
   
3. During this engine‑braking phase, the solenoid opens, giving full oil flow
   

I now use this technique during everyday driving:

• Approaching a roundabout
  
• Slowing for a traffic light
  
• Anticipating a stop or speed reduction
  

This lets me increase lubrication until the oil reaches a healthy temperature (around 70°C in my case).

Returning to Normal Drive Mode

In most situations, once the car slows almost to a stop, it automatically reverts to D.

If it doesn’t, simply:

• Pull the right paddle for ~5 seconds
  
• You’ll be back in full automatic mode
  

One Important Caution

Be careful to avoid an accidental double‑pull of the left paddle—this can happen if the wheel is turned and the paddle isn’t pulled firmly.

A double pull tells the gearbox to:

• Recalculate the “best” gear around 3,000 rpm
  
• Then downshift one more gear
  

This can easily land you at 5,000–6,000 rpm, which I personally try to avoid when the engine is still cold. I’m also not convinced the 7‑speed in the S212 has the same over‑rev protection logic as the later 9‑speed in the 2018 A205, which prevents downshifts that would push the engine past ~6,500 rpm.

My Long‑Term Experience

I’ve been using this method for over a year, quite intensively. So far, the engine runs perfectly and I haven’t noticed any negative effects. Again, this is just my personal experience—not a technical guarantee.

Hope this helps anyone who’s been wondering about manually triggering the solenoid without modifying anything. Happy to hear other owners’ observations or corrections.

 

I will leave you with a famous quote from the Tappet Brothers who used to have a syndicated radio show about car maintenance in the US"

Both brakes and transmissions can slow a car down - which one is cheaper to repair ?

Imho unnecessary and frequent use of an auto trans to downshift and slow the car is a great way to meet your local transmission repair shop many years ahead of schedule.

 

@thparent Very interesting find. I am not sure why slowing down or braking deactivates the solenoid. With the solenoid unplugged, my oil pressure is somewhat linear from idle to the pressure limit around 60 psi. I should say that it climbs linearly and hits 60 psi (actually around 55 psi) long before even 3000 rpm.

Since the transmission downshifts quickly in S+ mode when applying the brake, I think the 7G+ transmission can handle downshifting. I do agree that long-term use of the manual mode (triggered by the paddle shifters) may not be the best for the transmission, but only because a Google search will have every “expert” say constant manual shifting leads to early wear. Who really knows?

WRT over-rev protection, I know my 7G transmission in a 2004 SL500 I had would upshift and downshift while in manual mode if I hit redline or slowed down too slow for the current gear. Both actions were probably to protect the engine.

Since I like having unrestricted oil flow all the time for lubrication and piston cooling, I just unplugged and added a sacrificial solenoid to avoid any DTCs. I’ve been that way for over two years. I also change my oil every 3000-5000 miles.

 

I have no rationale explaining why the solenoid is full open when engine braking but it is reported as so in Xentry (when driving,as soon as you release the accelerator, the solenoid is reported "open")

I agree that brake are cheaper to replace than gearbox, but I'm not sure that it is my point (I'm still using brake). It's just to highlight that in my day to day driving there are almost no time where the solenoid will be fully open and therefore fully lubrificating the engine/cylinder ...

Thanks to @TripleDown , I discovered that my gearbox was not a AMG 7 MCT but a 7G-Tronic (plus) like for many (to not say all) of the E63S 4matic.

I believe that one of the key element is the fact that I'm not forcing the speed downshift but let the TCU manages it by applying a long pull (maybe the reason why there is a significative delay (several seconds)).

On the basis of my research specifically for the 722.971 (torque converter) :

What the gearbox actually does during a long pull

On a 722.9, a long pull:

• cancels manual mode
  
• returns control to the TCU (transmission control unit)
  
• triggers a safe, pre‑programmed downshift sequence
  
• only selects gears that match speed, load, and temperature
  

So yes — this is effectively the same as “letting the gearbox do its own downshifts”.