Let's see, crudely converting for my Yankee brain, that's about 1 quart in every 6000 miles. I've had vehicles that needed oil more often.
Going from 5W to 0W would be beneficial for starting and FE in Finnish winter weather, but I'm pretty sure going to a 20-weight oil would increase the oil consumption.
That said, I have considered it on my Subaru. At 234,000 miles, it doesn't owe me anything, and I like experimenting. So I'll be interested to hear how the switch goes.
