Jeff,

From previous and current experience on a variety of transmissions, soot comes from the friction material, that very slowly wears down over a very long time, just a powdery substance that is suspended in the fluid and tends to cling to the wall of the transmission, completely normal from everyday use and product of the friction in the transmission when changing gears. You're right no combustion in there at all, that would definitely be cause for alarm.

It would be nice to see transmissions last the life of the entire car...

I Agree that the "No Reverse" website is a bite of a rant, but when dealt the 'No Reverse' cards, I too have already been prone to rant on about it, what a PITA! My problem is I haven't made enough money last year, where I wouldn't have to worry about this, and just take it to my trusty mechanic like old times. Lots of Money fixes everything with ease, and 2008 is the year, haha.

I wasn't meaning there was some conspiracy in place, I do recognize our modern engines run a lot better and cleaner, and the advancements made in fluids and components (well except the one that failed, in my case) have greatly improved. But I had a friend that is a BMW shop foreman, and his biggest issue was when they revised the maintenance program to 30,000km sometimes even more, a lot more cars came in with maintenance related glitches, and he said himself most cars, need to be serviced before that. And from a business stand point since BMW does pay for oil changes etc, it's cheaper for them to extend the intervals until this period is over. Primarily BMW has always used synthetic oils, which tend to last about 20,000km, but before this free oil service program was introduced they recommend 5 or 7,000km service intervals regardless, this is when you had to pay for it. That was my point, BMW seems to want you to do more of it when you have to pay and less when they have to, naturally.


Differentials, that is something else I also serviced, front and rear, they are also seal for life, and I have not done major off roading until recently for the life of my vehicle. But despite the front diff being a sealed system, my diff fluid was black like tar and ran like molasses. My rear diff however was only brown, I have personally noticed that for some reason the Front Diff does run considerably hotter, despite more of the torque supposed to be exiting through the rear wheels.... I did service the diffs again at the next oil change since I had done a lot of off roading, as this is good practice, however all was normal.

I think everything has a shelf life and everything eventually doesn't do its job as good as it once did, and since there is a lot of heat build up in the transmission i think whatever is in there will only be able to do it for so long until it stops. But noted I'm the one sitting here with no reverse and you are not.

Those are the reasons I believe in fluid maintenance, but you have brought up great points. I hope others find our rants useful, haha. Someone just has to come help me take me transmission out now.

Regards,
Frank