Replacing the rear differential oil on the W212 E350 CDI

[bl52krz]

I have just replaced the rear differential oil on the W212.

Mercedes Bevo designates Fuchs Titan Sintopoid FE 75W-85 as an acceptable lubricant, acquired on Black Friday from Opie Oils for around £10 per litre bottle (two bottles are required). I suspect that is the liquid Merc really included in their bottles. Refer to my previous discussion on power steering fluid and the Bevo link, which clearly indicates that Fuchs is the only certified supplier of PAS fluid; hence, Fuchs is evidently often used by Mercedes.


The drain and fill plugs on the differential use a 14mm hex key configuration. I own a Laser sump key set, which includes a 14mm sump key socket compatible with a 3/8" square ratchet drive that fits into the plug head. Thoroughly clean the drain plugs and apply penetrating fluid at least 15 minutes before to attempting to remove them.

I discovered that a 3/8" ratchet fit into the area between the exhaust, eliminating the requirement for a wobbling universal coupler.


I opted not to put a jack on the differential, using this alternative way instead; nevertheless, I cannot endorse it to others since I cannot guarantee the safety of the jack. I would only feel adequately at ease doing this service on MOT ramps or a four-post lift.
Many individuals may advocate for the use of axle stands; however, this necessitates the danger of elevating the vehicle only via the differential, which is already deteriorating after twelve years. I would not feel any more secure underneath two little axle stands with a very narrow base, especially when compared to a wheel and a three-foot railway sleeper. I believe that a wheel positioned correctly under the sill and the robust, square-cut wood under the rear subframe could adequately bear the car's weight if the jack were to fail. The space between the sill and the wheel, as well as between the wood and the subframe, was less than 5mm, indicating that any 'drop' would be minimal.

I elevated the passenger side rear, detached the rear wheel, and positioned it partially under the vehicle, next to the sill and in proximity to the jack, thereafter placing several substantial offcuts of railway sleeper behind the rear subframe. While under observation by an assistant who was well informed about the jack's operation, I manoeuvred under the vehicle, loosened the fill plug, and exited. Approximately 10 seconds.
Reattached the wheel and lowered it to the ground.

I subsequently elevated the driver's side, using the identical procedure as previously described, with a wheel under the sill and railway sleepers beneath the rear subframe. While being monitored, I was whipped below and completely removed the drain stopper, which I inadvertently dropped into the oil catch pan. Approximately 20 seconds underneath the vehicle.
I subsequently lowered this side meticulously on the jack, ensuring that the differential was inclined slightly downward towards the drain hole.
After allowing it to drain for around 20 minutes, I elevated the car once again, ensuring the wheel and railway sleepers were in place, and reinserted the drain plug from under the vehicle. Approximately 20 seconds.
Subsequently, retract the wheel on the driver's rear and lower it back down.

Now, return to the rear passenger side, elevated with the wheel removed and placed under the sill, together with railway sleepers once again. I was able to access the fill plug between the brake disc and the front of the rear wheel arch using several socket extensions. Additionally, I utilised a large oil syringe/extractor with approximately 2 feet of rigid poly hose to fill the differential, all without positioning myself beneath the vehicle. It is important to note that the car is inclined away from the fill hole, leading to a minor overfill of differential oil.
I then lowered the vehicle to a level position, allowing the extra oil to drain to the appropriate level.
Repositioned the vehicle, placed the wheel under the sill, and then swiftly crawled underneath for an additional 30 seconds to install the plug, followed by a brief cleanup with baby wipes.

The repetitive process of removing and replacing the wheels, along with raising and lowering the vehicle, extended the task to approximately 90 minutes. However, I felt more secure with the car resting on three wheels—one wheel positioned under the sill, supported by railway sleepers, and the front wheels chocked—rather than having the rear elevated on both sides with axle stands. This preference is particularly pertinent for rear-wheel-drive vehicles, as the front wheels are not constrained by gears or the brakes.

[stevenkeyte]

Excellent composition; nonetheless, please let me to provide one more point. When replenishing differential fluid, always prioritise loosening the filler cap first.

[bl52krz]

Indeed, I have completed that task, and it is detailed in the preceding article.
I may have been editing as you sent this remark; I apologise for the delay in my response.
I transitioned from typing on my phone, which was very sluggish, resulting in an incomplete thread being submitted. I then continued on my PC to use a keyboard. 👍

[stevenkeyte]

Indeed, you did; I own my error. I have elevated my C55 through the differential once or twice, however it is somewhat cumbersome since I must first remove the metal heat sink. Elevate the vehicle on one side, remove the heat sink, lower the vehicle, position the jack beneath the differential, and repeat the process. You comprehend the concept. Severe pain.

[markjay]

I have performed it three or four times on each vehicle throughout the years. Due to the incline of my driveway, I position the rear of the vehicle upon wheel ramps, thereby levelling the car.
I have consistently used Fuchs and an inexpensive eBay transfer pump, which simplifies the refilling process.
It is an inexpensive endeavour as a do-it-yourself project.