I would say use the same mixture (generally 50/50) as for cars.
The suggested mixture is to achieve the lowest freezing point and thus the best possible protection against freezing and bursting.
(One morning on WRKO Radio) The tub's not clean! Let's remodel the bathroom.
(One afternoon on WRKO Radio) It's time for an oil change. I'm going to trade in the car for next year's model.