I have an '09 z4 35i with the same engine as your 335i: the N54. This is a twin turbo direct injection motor, i.e. high heat shear and significant fuel dilution. Do a search on this forum for N54, 335i. etc. to see results of UOAs and problems associated with turbo direct injection. The BMW High Po oil is probably a grp III base stock. It works perfectly well in a naturally aspirated BMW, but is just not up to the rigors of the N54 (I'm beginning to wonder if any oil is). At 1500 mi I dumped the BMW oil and did a UOA. The oil had already sheared back to a 20 wt and the flash point was dropping below 400 - - at 1500 mi OCI. I have seen similar UOAs on the N54 and now the N55 on this forum. It is a testament to BMW metallurgy that these motors stay glued together. But the issue is not so much accelerated wear but rather deposit formation in the intake tract (which appears to be a problem with all direct injection motors), which can eventually affect performance. Anyway, I'm currently using German Castrol, Castrol Syntec European Formula 0w30. It is a grp IV base stock with a cut of ester. I'm doing 2000 mi OCIs and the oil is barely hanging in, but it is at least staying in grade and the flash point is hovering around 400, with about 1% fuel dilution. Some of the other oils mentioned by Ibrahim might do better (you just have to experiment with UOA verification). You need to focus on 100 C viscosity, flash point, and % fuel dilution on the UOAs (and maybe do these with an ISO-certified lab that will give the most accurate readings on the last two). Redline 5w40 looks promising on paper, but beware it has relatively high ppm of antiwear zddp (not shown on the spec sheet) around 1200 ppm, which is much more than your BMW needs. The 335i and most other BMWs now have cats as an integral part of the exhaust manifold; in other words close to the exhaust ports. If you are burning any oil and running a high zddp oil you run the risk of ruining the cats. If you are adventuresome, run the Renewable Lubricants, Inc 5w40 oil. It is vegetable based but has the reputation of being to stand up to the fuel dilution.