[BadakVT]

Every two oil changing..............which means 370500 miles.
I tried to do it this afternoon as I've reach this mileage.
Unfortunately, I think BMW has done everything possible to not let you work on this car by yourself.
Every operation needs a special tool
And the spark plug socket I have bought seems to be too thick !!
Has somebody tried this one and is it OK ( it's written yes, anyway ) ??
https://www.ecstuning.com/b-schwaben-parts/14mm-deep-well-spark-plug-socket-3-8-drive/001247sch01a/

Thank you

Hi Boubi, that socket is the one you need. I had to buy one when I was changing my plugs as well. Newer Nissan cars also use the same socket.

As far as the plug change interval, my dealer told me 60,000 miles/100,000 km for a stock car. Change sooner if car is tuned. Anyway, plugs are cheap and changing it earlier wouldn't hurt.
I had mine changed at 15,000 km to BMW Hi-Power plugs for Bytetronik stage 1 reflash and the old plugs were still in very good condition.