billyhead1

Anyone know when you're supposed to change the rear diff fluid? TIA

Glyn M Ruck

Benz documentation is inconsistent in this regard. Some says never ~ only top up & some says every 300,000 Km's or 10 years.

We have general concensus on the forum that every 100,000 miles is a good idea.

mis3

My car is 250K KM now, maybe I have to change this fluid soon.

Is this a big or small job? I prefer to use MB fluid, do you guys have the part number for 2004 CLK320?

Glyn M Ruck

You can only get it at the dealer so just ask them for it. You don't need much.

Dead easy job.

Benz only likes one additive system for their axles. The additive system is sacrificial so ultimately it's depleted. It will go a long way though.

Approved 235.7 products.

Fuchs TITAN SINTOPOID FE 75W-85 Fuchs Petrolub AG, Mannheim/Deutschland
MB 235.7/ 235.74 FE-Hypoidgetriebeöl A 001 989 33 03 Daimler AG, Stuttgart/Deutschland
Mobilube FE 75W-85 Exxon Mobil Corporation, FAIRFAX, Virginia/USA

ALLDATAdiy INFO

Alldatadiy.com has the complete maintenance schedule at your fingertips! Good Luck!

mrtremere

It's easy I did Jeep every few months cause I was going through water.
Just buy good fluid with the additive and a pump. My Jeep could be done without a jack but the CLK would need to be lifted.

Basic Video. This is automotive 101. I think its every 30k for most vehicles.

mis3

Sorry, I am confused. You said I can only get it at the dealership but then you named 3 choices.

Glyn M Ruck

Yup - sorry. You can try & get the other 2 but most people can't find anybody that stocks them other than in Europe. All are made with the same additive system.

mis3

I usually own a car for 4-5 years and then buy a new one. I have been driving my 2004 CLK320 for 8 years now and this is a first for me.

Therefore, I never had to change the differential fluid of the other cars. I am surprised that my dealership never mentions about this fluid change.
What are the benefits of changing this fluid? What are the symptoms if this fluid is depleted or too old?

I called MB and guess what? This fluid is life-time at well, like the automatic steering fluid. After the "life-time" ATF, I am not sure anymore.

Glyn M Ruck

As the Sulphur Phosphorus additive depletes so you will start to scar the crownwheel & pinion resulting in noise/whine.

It's also a good idea to get the crap out of a diff now & again. Diffs generate quite a lot of wear debris & if the magnetic plug can't hold it all & some gets in the pinion bearings you will loose preload.

You are starting to use the true mileage capability of a Benz so change the diff oil.

mis3

This is the life-time ATF situation all over again.

I called MB and my indie, both said I should not touch it. My indie even said that since my car is high-mileage, I should not disturb the differential.

When I had hesitation when stepping on the gas last time, I suggested to him to clean the MAF. He said the same thing, do not disturb the MAF.

I did some research, this fluid change will need a pump to put in the new fluid. I may have to do this in the dealership. My indie probably does not have the equipment.

Glyn M Ruck

You have two choices - take the back cover off to change the oil & replace the gasket ~ the hard way.

The easy way is to suck the oil out of the filler hole with a syringe & flexible tube. Then pump a litre of oil back in. Why some dealers & indies make so much drama of a very simple procedure I simply don't know.

Diff oil does last a long time but it does not last forever.

https://mbworld.org/forums/c-class-w...nging+diff+oil