BlackOmega

Hey everyone,
Doing some spring maintenance on my car and am getting to change the rear end fluid. However, I googled which fluid it takes and really didn't get much of an answer.

Through ShopKey pro, it says I can use 80/90 (or was it just 85/90) or SAE 90 weight.

However, knowing that MB's like certain types of fluids, I'm trying to make sure it's compliant with my rear end due to the limited slip.

Which MB spec does the gear lube have to meet? 235.7? 235.8? I was going to use Mobil 1 LS, but that is not compatible. I've read that the Mobil 1 Delvac 75/90 is compatible with E-4matic's diffs. Just wondering if the E55's used the same stuff. (Am debating on getting the 80w140)

Then on to the trans. I have a slight leak on the front pump (not really a big deal, just time consuming since I'll do it myself and annoying). Is there a non synthetic fluid that can be used in it until I can replace the seal/filter/gasket? I've been adding Pentosin ATF1, but at almost $18/liter, I'd rather use something else cheaper.

What is the fluid spec for the E55's transmissions?

I found this handy MB fluid spec chart, however, I need to know which spec. When you click on the spec, it tells you what compatible fluids are.

Nocturnal-G

Not sure which spec is correct, but I do know 85w90 is correct.

You can try calling the dealer for spec. Usually newer specs are backwards compatible.

desired_speeds

I replaced my diff fluid with Amsoil 75w90. Yes I know its not the factory recommended weight, but its been fine and it never gets too cold around here anyways.

saintz

For cheap trans fluid there is Shell 134 that is MB approved. I would not use non-synthetic, even short term. People have had serious transmission issues occur in short time using wrong fluid.

The fluids should be backwards compatible, so the 236.1X versions will generally work in the 5 speed. Most that you find will be for the 7 speed specs (which have several numbers based on new versions).

See this: http://www.benzworld.org/forums/w210...-236-14-a.html

BlackOmega

SAE 90 is also correct from what I've been reading. However, the SAE 90 has to meet a certain military spec (forget the number off hand).
AMSoil is great stuff. I haven't had any issues with it in the vehicles I've used it in.
The weight you used is not exactly what it calls for. But I'm sure it'll be just fine as long as it has the proper limited slip additive.
In regards to weights, usually the lower the number numerically, the lower the viscosity. Viscosity is the "thickness" of a fluid. So the more viscosity something has, the "thicker" the fluid. i.e. honey has a much higher viscosity rating than water.
So you're actually using a thinner fluid. MB specs thicker fluid which resists shear stress, wear and tolerates higher temperatures better because it stays, relatively, thick at high temps. NOTE: With all oils, the hotter it becomes, the "thinner" it gets. That's why you don't hear about race cars using 0w20 motor oil, because when the engine would get hot, the oil would get too thin and cause a catastrophic failure.
Thanks for the info. I'll see if I can locate this stuff locally. There's a import car parts place close by that stocks a lot of Euro spec fluids. They even stock ELF oils and such. Great place.

Thanks again for advising about using non-synthetic fluids. My leak seems to vary by the day. Some days it'll leave a quarter size drop, another it's the size of a platter.
I think I may pull the whole drivetrain and just reseal all of it. It seeps from the valve covers and the rear main as well (definitely doing the rear main when the trans is out).

Do you know what the actual spec for the late W210 AMG's is?
Also, would you happen to know what the actual numeric designation for the AMG trans is? Or where I can find it?

saintz

The AMG trans is 722.6 something or other. You can probably find the exact number on the Russian VIN decoder. All the 722.6 use the same oil (I think) but have different torque maxes based on various valves and such.

The valve covers just need to be tightened. Common problem on Mercedes V8. Just torque the screws down (not too tight, aluminum heads). Only if they still pour oil should they be changed. Rear main seal affects every MB with miles. Change it only if convenient or pouring oil.

Check the shift linkage and TCU cable. These are both common trans oil leakage places.

BlackOmega

I've done some reading about it and have found that which 722.6 trans you have, depends on which engine it's behind. 4/6 cylinder applications have a different 722.6 than the v8/v12 engines. The two versions are geared differently. Even though they're the "same" transmission, the gear sets aren't interchangeable due to the pre-programmed parameters within the trans computer.
It would be awesome if you could interchange them since first, second and third are steeper in the 4/6 cylinder transmissions, which would make the car accelerate faster off the line, yet it retains the same gearing for 4th and 5th; so no loss of fuel economy when cruising.
The valve covers are just seeping a bit. So I'll try tightening them down.

The rear main is leaking. More than a seep, but not pouring.

I only wish it that was the case. It's leaking right out the front where the input shaft is. I've heard that there's a bronze bushing (usually) that wears out and allows the input shaft to wobble slightly and wear out the seal. So even if I were to just replace the seal and not the bushing, the leak would reoccur within a relatively short time, like 10-15k.

And I figure, while I have the transmission out, I'll just replace the rear main seal while I'm at it. (Unless it involves dismantling half the engine to replace).

I'll be sure to post pics when I do it.

Thanks for the tips.

Nocturnal-G

Do you think certain motor oils can replenish the seal? I've been doing quite a bit of reading, trying to figure out which motor oil I'm going to buy. Same with Trans fluid...

I've read group IV and V, ester based oils help with seals... I could be wrong since I'm barely learning.

saintz

Using the wrong oil can damage a seal and exacerbate a leak. Switching from the wrong oil to the right oil may fix the leak. But there is no magic oil that will fix a leak if you're already using the right oil.

There are radiator stop leak products that can seal a radiator leak. Unfortunately nothing like this exists for oil leaks. Anything that would stop a leak would also cause unintended problems, like blocking oil flow to some critical part of the engine.

Just use an approved oil and you'll be ok.