Can anyone explain to me why BMW uses 20W-50 oils? Is their a valid reason that 10W-40 is not recommended? "K" bikes are water cooled lower RPM bikes similar to some of the newer cars that run in the 3500 - 4000 RPM range.
To the best of my knowledge most newer cars run 5W-30, 10W-30 or 10W-40.
I am just curious since 10W-40 is very common and a lot less expensive. I change oil every 3K.