What oil to use in three new eXmark HP's..?

Hi. I would like to hear both the "official" exmark recommendation, and also what oil other owners use in their exmarks.
Between my brother, myself , and a guy at work we have 3 exmark HP's. Mine is a 23hp Koeller, my brother's is a 17hp Kaw, and my buddy's is a 23hp Kaw.
Mind you these exmarks are mainly residential, (at lease 2 of them), so they will only have about 45 hours per year on them.
Two are brand new, still having the "break in" oil in them with less than 5 hours on them, now ready for their first oil change.
We are thinking of using a synthetic oil, like AMSoil, or equivilant.
The exmark manuals do not seem to advise that much...it just says "any 10-30 oil" for only summer use.
After upgrading to something as nice and expensive as an eXmark...I want to baby it with the best. Thank you all in advance for your help and advise.


Manufacturer / Sponsor

Here's the official scoop on oil. Per Kohler use a 10W30 or 10W40 during the summer months. Per Kawasaki use a straight 30 weight during the summer months.

Neither manufacturer recommends the using or not using synthetics. Kohler will state that in hotter climates a synthetic can be beneficial. Both manufacturers feel petroleum oil does an adequate job of protecting the engines.

My official response is this. The synthetic oils will protect an engine better in my opinion. Please keep in mind that I'm not engineer or anything like however. If it were my engine I'd wait until the second or third oil change. This helps ensure that the rings, bearings and other components are properly seated.