The oil type recommended in Kawasaki’s manual is 10W-30 or 10W-40. For most FR691V engines, the factory dipstick says 10W-30 right on it. Historically, Kawasaki has referred to 10W-40 as the right engine oil for general use on these engines.
For temperatures above 90°F, Kawasaki recommends using 10W-40, 20W-50 or 15W-50. In the recent documents from Kawasaki, 20W-50 is listed as acceptable for any temperature above freezing, as using this type of oil can reduce the oil consumption that was being observed with 10W-40 and similar weights.