[Mike Halliday]

 My bowser washer will be staying on the drive this winter I know how to protect the pump but any advice what I should do to the engine, not just to protect it from the cold more about the 6 month it will be stood still until I next use it.

It a air cooled kholer 18 hp

[BDCS]

The engine will be fine - keep the battery charged up and start it every now and again. Usual things like good connections, spray with wd40 and cover it with a blanket and tarp. Don't let the petrol go stale.

[Blast Away]

6 months?!!! 

[BDCS]

Whats wrong with 6 months - I'm sure if you earnt enough in the other 6 you'd kick back in the cold dark damp depressing winter months. I would but I'm on the bread line 

[Griffus]

There's an additive for petrol that stops it going off. I use it with the bikes. I'll let you know what it's called when I get chance.

The other option is to completely fill the tank as it's the more petrol / less air also helps preserve the fuel, or so I believe.

I'd just wrap everything up and keep as dry as possible.

Couldn't you do a deal with a local business to store it inside over the winter? Worth a try.