I doubt it's oil-related. And if you're in the snow belt, I'd stay on 10w30.
Given what you've said, I suspect the problem lies in valve lash...If the valve adjustment wasn't done properly, it is possible for them to be out of spec already.
Just to be safe, I'd go back to the shop that performed this work and ask them to check the lash again. I know it sounds absurd, but better safe than sorry.
h: