Forever transmission fluid

[Arminius]

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!