I would also like to mention that 10w-60 is being used in new BMW engines, which right now have all the HP they can pull from them. Now, why would BMW require 10w-60 if it was too thick to get to the bearings? Also, no offence, but pulling a source that uses a worker at Amsoil can not be justified. The only true tests are provided via an independent, unbaised, research company. Maybe it's just me, but with even 5W-30, I would be afraid of VANOS rattle the whole time.