Just finished my first 24K maintenance and everything went well thanks to all the information on this forum. My question now after looking ahead for planning on the 36K maintenance, is it really neccessary to replace the timing chain slide rail, tensioner rail lining and thrust piece every 36K per BMW recommendations or for that matter to even inspect them? Is this a BMW make money issue? It appears to me to be a lot of work with small payback. Am I wrong?