I'm not sure this will help but maybe:
I have a TC35A. I live in north central Texas which might sound hot (and it's warm compared to where you are) but currently it's not been over about 35 degrees F for most of the last 5 days (it's 19F now). I use Shell's Rotella T Synthetic 5W-40 and have no problems with the tractor and I've put about 200 hours on it since it was bought used with 300 on it. I use the same oil for my 2002 Dodge 2500 with the Cummins engine, my 2006 Pontiac G6 V6, 1999 Trans Am, and my 2004 Honda Shadow Sabre 1100. The Dodge has had the oil since about 20,000 miles (now at over 150,000) with trips to MA in the winter, the T/A for the last 2 years, the G6 since the first oil change (it's now at almost 60k miles), and Honda since it's first oil change (now at almost 26k miles). No problems from any of the vehicles, tractor, auto, or motorcycle, whether hot weather (100+) or cold weather (<20). Not nearly as cold as you'll see there, so that may not help you.
FWIW.
--HC