I have a short version tech manual on the CVT from ZF. It's not a sealed unit, in fact, ZF recommends that you change it's oil every 45,000 km. The top fill plug is right under the forward side of your battery box, which must be removed to gain access, but don't sweat it, it's easily removed with 10mm bolts inside the box on the bottom. The fill plug is removed with an Allen wrench, as is the drain plug on the transmission oil pan. Look under the car to the transmission oil pan to see what the top plug also looks like. Just like on American automatic transmissions, there is a filter, accessed by removing the oil pan. Judging by the color of the oil I drained out, I say change the trans filter more often than recommended. If you have engine mods like I do, you'll stress the all-metal drive belt more. It is cooled and lubricated by an oil jet spraying at the belt. My manual says that 'Higher torque applications use a 30mm belt, rather than the stock 22mm belt'. I don't know if any mods need to be made to replace this belt with the more stout 30mm one, but if I break mine I'll be finding out. I suspect that the CVT design takes less power to drive than a conventional transmission, as it looks like there is less spinning mass. I think that I will stick with this type transmission and try to iron out flaws as they show themselves- especially since it seems that all the other transmissions blow up when you drive this car as a performance car. If anyone has changed to the 30mm belt, please let me know what mods,if any, were needed. -Jeffy.

 

This is good info, keep it coming...

I thought the CVT required some special fluid that was different from regular ATF - is it possible that the fluid that you drained was that color because of the nature of that special fluid?

 

bonk! for the sake of Jeffy, i hope not.

 

No bonk intended, it was an honest question - it seems like everything in these cars is different than the "standard" or "normal" that applies to more mainstream cars.

 

For some reason BMW doesn't give any clues to the nature of the CVT trans fluid. Is it like engine oil or ATF? I had poured some used stuff into a glass bottle and it remained dark and opaque, which is not like any automotive lubricant I know of. So, I couldn't determine contamination by that alone. I'd rather buy oil and filter more frequently rather than a new transmission. Judging by the ZF manual I have, they seem concerned about the drive belt slipping causing excessive wear. Also, there is a heat sensor that will cause the clutch to slip less if temps get high. I want to know about the 30mm belt option. I think that I will need to go to the ZF Getriebe web site and get info from them, since BMW wants to keep these things secret, but the transmission is not a BMW design, and this transmission is used in other applications (I don't know which cars). They are more likely to give us oil requirements and say if the bigger steel drive belt can be installed in our transmissions with minimal further modification. I will post what I find out. -Jeffy.