Darren Woods fitted my catch can, so they've practised it on my car! They charged 1 hour (£40) but it involves taking off the scuttle plate (pollen filter cover etc) and decorative cam cover off along with a bit of pipe cutting and re-routing.
Based on sound advice from Tony (as usual), quite a few 335i owners on here have started using Silkolene Pro-S 5W-40 full Ester sythetic race oil. (its called Fuchs Titan Race Pro now)
Read spec here - http://www.opieoils.co.uk/p-68897-fu...ngine-oil.aspx
The 335i runs quite hot oil wise, the thermostat seems to keep it at 115degC minimum, 120 or so in traffic on a warm day, and mine flew to 140deg on a warm track day and mine is not mapped.
Oils are graded at 100degC so this means the already thin 5w-30 will be even thinner at 120deg+ giving less protection when hot. Using 5W-40 gives the same cold rating as 5W-30 but is thicker at normal running temps.
It's also cheaper than Castrol edge and outperforms it handsdown in every area. Its not LL04 approved but that's irrelevant as you won't be leaving it in for 18,000+ miles will you?