Was it the sulphur in the transmision fluid of my 1999 ML320 that allowed Daimler to recommend against changing it ever? There are 211,000 miles on my truck and I decided to change the fluid before taking a long trip in order to examine it, the pan, the filter, and the magnet for debris suggestive of failure; luckily, there were none. What I did find was black fluid the consistency of molasses which stunk of sulphur and left a yellowish stain on my jeans. I think it was hypoid gear oil like what I used to put into differentials and boat gear cases. The expensive replacement fluid has the appearance of brake fluid without the sulphur. Apparently Daimler now recommends frequent fluid changes. Was Daimler forced to discontinue use of sulphur for environmental reasons or did they go to the lower viscosity for MPG considerations? I liked the idea of forever fluid and wonder what has changed. Daimler gets more money this way and I heard that when the new parts boss came in about 10 years ago, the first thing he did was double parts prices to corporate acclaim. They are a sinister, sulphurous bunch!

is your transmission a manual then it would be gear oil.If automatic the clutch have graphite in them and cause the black,nothing to worry.Tramission should fluid should be change every 40,000 miles.I use Mobil One ATF and change every 80,000 miles.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran, deutschland deutschland uber alles uber alles in der welt

As "Forever" ATF.(Except in the mind of the Deceived Owner!)
Most Likely some Madison Avenue Type working for Montvale or Stuttgart
came up with THE RIDICULOUS claim as part of some sales Smutz.

MB has backpedaled away from that Bushwa claim as fast as they can,
and at the same time managed to try to appear as if they NEVER Said it.

TOO,TOO Many Trannys went KaBoom as a result of this Excrement!

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'84 300SD sold
124.128

Not sure how or why it would smell of sulfur. I've heard the special ATF is much like Dexron, though the additive package differs.

The black is normal. The clutches in the transmission include graphite, and the fluid picks it up over time as the clutches wear. Inky black is not a problem, though it does indicate the trans has not been serviced for many miles.

The filled-for-life thing was an MBUSA policy. The Rest-of-the-World always had a 40K-ish mile service interval for this transmission.

My 99 c280 with the m112 has the tranny dipstick /filler tube sealed. How were you able to add the fluid?

I'll do a separate thread under "Change ML320 transmission fluid" as there is a lot of misinformation out there.

Sulphur has long been a additive for oil to be used in gears experiencing high pressure and sliding contact such as hypoid sets. Daimler doesn't do anything without cause. I wonder if high sulphur transmission fluid in conjunction with an instruction to purchasers to never change it may have been a factory experiment. I use my tranny fairly hard with gutted converters and extra intake air. Also, I go down through the gears at stoplights as on my motorcycle. I don't tow over the Pass as my last Tahoe went out at 120,000 miles despite the addition of a separate fluid cooler. This was good fluid for me. Factories do experiment like Harley did with OHC drive belts instead of chains (now the norm). If this were an experiment, there are other reasons besides non-functionality which could have caused its discontinuance: EG, reduced profits to dealers for service, the Euro eco-nannies or MPG. Just another one of life's mysteries. I'd prefer not to change every 40k.

A lot of european manufacturers went to 'lifetime fluids' in the 90s so they could claim lower ownership costs over the life of the car. Its BS. My 94 Volvo had lifetime diff oil, ATF and coolant. Replaced all 3 more than once.

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CENSORED due to not family friendly words

I would maintain that the transmissions went boom "just because". There is no way to prove whether a transmission would fail if the fluid were changed or not. Transmissions sometimes fail, through no fault of the fluid.

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Mercedes gave upon the idea of lifetime trans fluid about 2004. You are very lucky the trans hasn't expired.

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Roger E.