I have seen here that others have used 10w-40 oil although the manual specifies 10W-30. On my shelf I can choose from Mobil 1 full-synthetic 10W-40 motorcycle-specific oil, or Shell Rotella T5 synthetic blend oil, not specified as motorcycle, but neither is it stamped with Energy Conserving, or the like. Would either be more desirable than the other? How might shifting and clutch action differ between the two in use?