Which Xw-20, brand name, dyno, blend or synthetic, miles at start, total miles, your vehicle, weather, driving situation and habits? Details, please?

Quote:
I asked the questions becase I have a new Prius, that calls for 5w-30, but I was thinking of using Red Line 5w-20 which is a thick 20 weight. It's rated at 9.1 cSt at 100F and I think that 30 weight starts just above that. It's a company car and if I like it I'll buy it, if things work out.