I changed the transmission fluid in my 335i half a year ago near 90K miles.
STRONGLY recommend changing the mechatronics sleeve while you're at it. I did not and had to do the service TWICE cuz of leaking transmission oil. The mechatronics sleeve is cheap.
Also when I bought the kit it only came with 6L of oil. Not sure what the capacity was in the 135i but I had to purchase another 3L at dealer prices to complete the fill.
Just a few tips to ensure you guys don't make the same mistake I did
