pmak

Does the years living in UK can be counted towards the OAS calculations? I know the fact that max OAS calculations require the 40 years residency in Canada.

bats

no

BristolUK

I think Bats is right. I could never find anything definitive on it, just that general "time spent in other countries may count" and you might think that given there are some reciprocal arrangements between the two countries that it might.
But given time in the UK (National Insurance) may qualify one for a UK pension, it wouldn't seem right for it to count double if you see what I mean.

What I do know is that last year I qualified for partial OAS and it was very obviously based solely on my residency years in Canada.