Things I learned talking with a 30 yr BMW dealer mechanic

The OEM rear sway bar brackets on the original E39 weren't up to the job and he has seen them break on new 1000 mile E39 M5s driven only to work by businessmen. It's such a common problem, that he see sees broken brackets and links on over half of all the M5s that come in for service. BMW has upgraded the design three times, and they are sturdier now, but the TC Design and beastpower brackets seem to last forever. This is a job that is not that hard to do yourself if you can get under the car safely with ramps.
The question of oil and using 10w-60 (Ten W Sixty = TWS) on the M5 has been beaten to death. His observation was that of all the high mileage, over 130,000 mile M5 S62 engines he's seen. The healthiest ones have been run on a regular diet of TWS. He told me of one 235,000 mile S62 engine on a 2000 M5 he saw with the original rod main bearing caps that had been run on TWS with religious 3000 mile oil changes its entire life and had good compression in all the cylinders. He looked me in the eye and said don't skimp on oil changes and only use TWS.
He's only seen three true S62 VANOS failures in his career (two of them were from racing abuse), the main VANOS problem comes from the solenoids and it's an easy fix. The VANOS is the most unfairly maligned part of the engine and there's nothing dangerous or wrong about a little VANOS noise at engine start up on high mileage engines.
When it comes to clutches, keeping the clutch pedal depressed at stop signs will wear your throw out bearing at a much higher rate than if you just keep the car in neutral and shift into first when the light changes. One man ke knows who works downtown has had three throw out bearings in 100,000 miles because he likes to keep the clutch pedal depressed at stop signs. As for clutches, most early replacments he's seen, have come from driver's that admitted they use 2nd gear a lot from a stop instead of that stump pulling 1st gear. Always use 1st gear from a stop and try to rev match when you shift. He has seen original clutches go 120,000 miles on the M5. It's the one part BMW's M division really overdesigned.
Changing the brake fluid is the most often neglected service item on the M5. It's important to have a dealer flush the brakes because they will flush the clutch slave cylinder line too, which is connected to the brake fluid and it gets the dirtiest. Auto shops and private individuals rarely flush the clutch slave line. After being flushed it's important to make two or three hard stops to purge the system - Words of wisdom from a 30 yr BMW mechanic.