0w20 in a JD F510 with Kawasaki PA540V 17 hp ?

My F510 has been retired to trailer hauling mostly anymore. And used a lot under 50F. It never really gets warmed up though as it's mostly start and go, then turn off. I do let it run for the first 15 minutes or so when it's cold out. But it's always been a slow cranker when cold. I use to use 0w40 and now have 5w30 in it.

I don't anticipate any long time running in the summer use.

So 0w20? or what?