What ingredient spec is it? Is it API SG compatible? If newer gen (API SJ and on in alphabet), I wouldnt buy it - can be bad for you engine in the long term
Nope, they aren't - it's another marketing bollocks to make you buy it since it's cheap by using cheap ingredients.
Air-cooled engines have much higher tolerance (read: slack) and temperature variations over operational cycle than the thin modern oil can fill the gaps since they're designed speciefically for the tighter water-cooled engines that dominate the engine industry of today, plus an additional consumerism factor of making things cheap.
When you plan to keep bike short time then there's no worry of course, you can run on a vegetable oil if you like to, but if you plan on making 100-200K+ miles on your bike and still be able to run the original engine then the matters can be different.
API SG spec (i.e. compare BMW and Golden Spectro with others in graph) has enough zinc and phosphor levels required for the robust air-cooled engines. It's not just the BMW, but Moto Guzzi and Ducati have issued similar official warnings about using modern-spec oils in their air/oil-cooled bikes in the recent past since people have experienced major engine failures since those modern oils tend to be made cheap by not having enough wear-protective additives such as zinc, magnesium etc (expensive metals and requires technology to make them as oil additives in the right amounts = too costly by consumerism standards). Doesn't mean you have to buy an expensive oil, but I reckon one should think twice when buying the cheapest oils available.
Have you ever wondered why the brand new OEM BMW branded oils you can buy today for your boxer are still based on that "obsolete" API SG or SH spec not some "bacwards" compatible new spec oil as SF or SJ? And why-o-why that "obsolete" SG oil is still being produced today? There's a small but a healthy market of oldschool-design engines still running.
Can't find the newer similar European market warning, but here's an older US BMW's official warning on using new generation oils in your air/oil-cooled boxer.
Since it's an oil thread - I'll get me coat now...
