What fluid, 500sec LSD?

[Somebody]

So, I finally got around to finishing off the maintenance stuff on my 500sec, and I drained out the diff fluid, however I am not sure what I am supposed to fill it with.

There is a tag attached to it saying something along the lines of ''warning use special limited-slip diff oil'' or something like that in German.

The stuff that came out of it was brown and didn't smell like any of the usual diff fluids at all. Usually diff fluid smells like GL4 manual transmission fluid, it has that really really distinctive smell that most EP manual transmission/diff fluids have, however the stuff that came out of my diff did NOT smell like that.

I have two types of fluid that I use in cars with LSDs here, one is LS80/90 and one is something 75/140, both are designed for LSDs. I don't remember what brands they are. I usually use the 80/90 in older cars.

So do I just dump the LS80/90 into it, or do these have some kind of weirdness going on inside which needs special fluid? I think some older style LSDs (like, real limited diffs, not just on/off locking diffs which a lot of older cars used) have some kind of odd clutches and other stuff that needs fluid with very specific properties.

By the way, as a matter of interest, does anybody know what type of LSD that thing is? Is it a torque/gear type, or that other weird locking plate type that nobody seems to know much about these days?

Thanks

 

[jaymanek]

80/90 is going to be the best option. If you have ASD it works by a locking clutch on each output shaft.

 

[Somebody]

Well, this just keeps getting more and more confusing.

I looked through the bigass manual I downloaded before, and it says that models with Limited-slip diffs, ASD (which, from what I gather from the wording in the manual, is a locker diff), and 4-matic all use the same diff fluid, which is MB 235.3. However spec 235.3 ( link: MB 235.3 - FE Gear oils (Specification 235.3) - Mercedes-Benz Specifications for Operating Fluids ) only shows 3 products, 2 are Benzes own and one is by some obscure British company that looks like it don't exist.

However, that page in the manual is called ''3501 - Oil change in the rear axle Model 107 from 8/85; 123; 124, 129, 140 up to 6/93; 126 from 9/85; 201 from 1/85'', and applies to LSD, ASD and 4-matic models. So the E class and SLs use them too.

There must be enough s-classes e-classes and SLs using lsds, asds or 4-matic systems for SOMEBODY to still manufacture the correct fluid for them?!

Dammit, why does this car need all these super weird fluids?

 

[Somebody]

Ok, well, I finally found a friendly MB shop where people were willing to actually talk to me, and I found out what the story with this is. In case anybody wants to know the answer, turns out these LSDs are really strange and need very specific fluid. Nobody makes that kind of fluid, it is not manual transmission fluid, EP fluid, or even limited-slip type gear fluid. Its something completely weird that no other manufacturer makes because its pretty much exclusively made for that generation of limited slip diffs and 4-matic systems made by MB. Later systems use a Fuchs Titan product, earlier systems use a normal EP manual transmission fluid, but that generation because of its weird design has to use that strange fluid. If you put anything else in there it can damage it.

Good news is its not actually that expensive, like 50 bucks for 2 liters, but the bad news is MB only stock it in Europe so it takes a long time to order, like a week or so.

 

[gm300te]

LSD Oil

Hi all,
I have the same problem with the blasted rear diff oil!
300TE 4matic 1991
ordered some oil from MB - according to my WIS - sheet 235.3
only to find out that the stuff is 'manual gearbox oil'!
MB must have changed specs in sheet 235.3

I would be very interested to know what oil you have found
so that I can get some

thanks
Gunter
Rochester, Kent