What temperatures are you usually seeing there in winter in Canada?
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Canada is a big place. Temps can/will vary tremendously depending on the location and the northern interior territories can see some horrible cold temps. Coastal areas are moderate by comparision.
I've often seen the T5 0W-40 on the shelf at the place where we get bait on the way up ice fishing in Ontario. I looked it over and on the bottle it said semi-synthetic but here on the forum was told it was actually full synthetic. Sort of an odd labeling/rating Shell was doing. If that is/was the case I'm guessing perhaps the "new" version is maybe just updated labeling or reformulated to join the T6 family and to pass the CH rating?
I would pick some up when passing through, but the stuff in Canada is so much more expensive than Rotella T6 here. Too bad we probably won't see it in the US.