Originally Posted By: jaj
I'm not going to argue about the choice of oils for the S62. BMWNA has published an updated recommendation saying "TWS" and as far as I'm concerned (having owned two E39 M5's and done endless oil analysis on the engines) I'd use it an be done with it. Someone asked what goes in the E9x M3's S65 engine in the winter, and the answer is TWS. For arctic conditions, your dealer will switch to something else for you, according to the manual, but I've never heard of it actually being done.
TWS was not and is not a bandaid for anything. TWS is the oil that BMW Motorsport (the racing division, not the "M" street car division) uses for all of it's factory race engines. It was developed jointly with Castrol in the 90's as Formula RS Racing Syntec, and when Castrol reformulated it's RS product from a Grp 4/5 blend in 2000, BMW bought the rights to the old formulation and kept using it under the "TWS Motorsport" brand name. That's why it's an API SJ oil. TWS is a true racing oil. It has a film strength on par with 15w-50 Motul 300V, way higher than any of the other street oils that pretend to compete with it.
So how did we get the dual application for the S62? Well, nobody knows for sure. In 2000 when the M5 was introduced into North America, the earliest cars had the low-tension piston rings that enforced the use of TWS. In March 2000, there was a running change to the engine design that replaced the low tension rings with a more conventional design. That allowed the engine to work with BMW's 5w-30 and other LL-98 oils. The change was global. The TSB at the time didn't stipulate that TWS shouldn't be used, it just went from required to optional.
The other engineering issue that occurred almost simultaneously was the introduction of the S54 engined E46 M3. It was first introduced in North America with 5w-30 in the crankcase. Then engines started blowing up, and the first reaction from BMW was to switch to TWS. Of course, the failures were not lubrication related - one set was caused by left-over casting sand in the engine oilways, and the second set was caused by mismanufactured rod bearings. A recall cleaned all this up, but once TWS was in the supply chain, it stayed, and S54's have used it ever since. My interpretation is that BMWNA attempted to reduce supply chain costs by having the M engines reengineered to run on 5w-30, and while it probably would have worked, other problems that happened at the same time scuttled the experiment. Now, TWS is available at every BMW dealership and BMW recommends it exclusively for all M S54/S62/S65/S85 engines. There isn't a lot of room to argue.
The sheets I was given by BMW clearly show otherwise (they are quite recent) as they tell me to run their 5w30 and NOT the TWS 10w60.
It appears even in BMW there is a lot of confusion here.
BTW, I'm not trying to be argumentative. It just appears there is no way to get a perfectly straight answer on this topic, regardless of who you speak to.
