Modern Kawasaki engines use a synthetic blend, which is a combination of regular oil and synthetic oil. For most applications they recommend 10W40. The thing with lawn mowers is that they are air cooled, which means that using the proper weight of oil affects the mowers ability to cool.
How to Choose the Right Oil for a Kawasaki Mower
Kawasaki is different from Briggs and Stratton, who recommend 30W oil for most of their applications. Use the oil chart above to help you identify what kind of oil you need for your Kawasaki lawn mower.
Only if you mow over 100°F would you need to add 20W-50. You can also see that 30W oil is only going to work for your Kawasaki engine if you live in a very temperate climate.