Understood that 15W-50 is heavier than 10W-40. But in reality will this really make a difference? I notice A&S's oil change kit for the F800 & F650 (twins) still shows 10W-40. They do have a "super synthetic" BMW oil in 15W-50 @ $45.00/gal. "recommended for all BMW motorcycles after 1970." in spite of what BMW Germany told fireman.peter above ("BMW has not released fully synthetic oils for the 800cm-ROTAX-2-Cylinders!"). A&S also recommends change the oil filer (& oil persumably) every 3,000 miles while the owner's manual says every 6,000 miles.
So, what's up with all of this? Discuss
Oh boy, another oil thread