Running engine with boat out of water

[<Edgewater1>]

I have a new (40 hours) Yamaha 4 stroke 90 hp outboard.

I have used the hose fitting on the left side of the engine to run fresh water through the engine, but have not run the engine with this as a source of cooling water. Can I? It would simplify running fuel out of the engine, and fogging it for winter storate.

With only 40 hours on the engine, should I change the lower unit gear lube, and, or, engine oil before shutting down for the winter.

Thanks

Gordon

[<boats.net>]

You can run engine on Flush Attachment at idle speed only

[<peter goedhart>]

The impeller wears very fast when running dry.