engine oil

[Walt Garcen]

What's up with Yamaha spec'ing 20W40 engine oil for warm weather use? I know that the 
viscosity curve foe 10w40 is a
little lower (some brands 10w40's may overlap other brands 20w40), but that's what I'm 
using basically because the brands
I typically buy are not available in 20w40. I'm assuming a lot of you are using 10w40. 
RSROB what's Yamaha's stance on
10w40 use? Have any of you using 10w40 had any problems with it?