I sure would raise "H" about the 10w 30 oil. That is way to heavy for cold weather like you experience in New York State and furthermore the Prius Engine does not run all the time, so it never gets as hot as a normal ICE car. I only have 4200 miles on my 2002 but I am thinking about taking my own oil (Mobil 1 5W30) along in when I get first service at 5,000 miles. I believe John in Minnesota has mentioned Mobil 1 (0W30) which I never have heard of. but it sounds good to me for that extremely cold weather up there. Just remember, the lighter the oil, the better the mileage!
Regards,
Don Good - Ephrata, PA
Regards,
Don Good - Ephrata, PA