Dave,
You make many valid points. But until Royal Purple at least shares some "general" data about the type of fluid BMW uses, I can not believe their broadbrush propaganda saying their product is fully compatible with it. By the way, is the OEM BMW fluid really straight weight or multiviscosity motor oil or ATF? That's a guess, isn't it! Therefore, it's a guess whether RP is applicable according to their own guidelines. Please ask them what type of M5 fluid they tested. This is a real simple question if they did it.
Reputable companies DO publish such info where they support an application. This is precisely why few reputable lubricant manufacturers support this BMW application. My strong suspicion is RP did not thoroughly analyze every manual application, lubricant and transmission component, especially the M5. You're talking many hundreds of transmissions and OEM fluids. It's safe to say such a claim is hogwash. Multi-billion dollar oil companies can't even afford to do that. More importantly, good science requires durability testing when the formulation is significantly different. Since they have proprietary additives, they need to test everything. This is what's necessary if you wish to declare your product as fully compatible for ALL applications using straight weight, multiviscosity or ATF. You're being fed a line of BS from RP. Same exact que cards that Red Line tech line reads to customers.
FYI, I will NOT keep the same fluid in there for life. I will change it soon. The question is whether I pay asking price for OEM BMW stuff or try something else.
As to your other comments:
Compared to the costly lifetime BMW factory fill, Royal Purple has infinitely more constraints when formulating their Synchromax product:
First, it's a severe compromise to develop a lubricant that is supposedly compatible with virtually every modern transmission on the market. This severely limits the additives that can be contained within the product. Certain highly effective additives that reduce friction, control corrosion, increase shear strength under extreme pressure & stabilize viscosity will attack a number of materials. Compromises in fluids are only made when necessary. Designing a totally compatible, organic & harmless transmission fluid like the Sierra antifreeze experiment is impossible and would be a severe compromise from a performance and lifecycle perspective.
Secondly, RP Synchromax was clearly designed with tremendous economic constraints to meet or beat it's direct competitors price-point, Red Line. It is orders of magnitude cheaper than BMW factory fill and they make no claims that it'll remain stable for the life of the vehicle. RP made it as good as they could to work in almost anything for $8/qt. Comparing BMW fill to Synchromax is kinda like comparing a big stretchy rubber band to a specific-length 5 rib serpentine belt.
Lupo,
Your post was laden with jabs about my anonymity and you described my technical post as a folk tale. What's up with that? I do not appreciate such jabs on this board or anywhere else. My reply was somewhat defensive, yet I provided contact info you complained was missing. The first-hand Getrag 540i troubles were posted by 2 roadfly members. Your accusations are misdirected. Please accuse them of BS and not me. I bet they'll let you pay their repair bill if you wager that they're fibbin'.
The specific deteriorating materials inside the Supra Getrags running Red Line (that cause shifting malfunction) ARE unclear to me, but their failure history was well-known. These problems were widespread until the word got around to stick with OEM fluid. The 5 series shift detent symptoms closely mimic posts made by Supra Forum members. I did not fabricate or exaggerate these issues. Why sweep this "inconclusive" info under the rug?
I sincerely hope you don't experience the hard evidence you "want" that alternate fluids can do damage. Your flaming closing statement in huge font was reassuring.