Hi bhvm,
My point wasn't 0w30 should be the right choice instead of 10w40. My recommendation was 0w40 or 5w40 if one wish to go for a thicker oil, but not a 10w40.
We all know, engine wears out the most in it's cold start and not in it's warm operating condition. If this cold start wear and tear happens even with the "manufacturer recommended" engine oil grade, then it's not a wise movement in choosing a grade which is less lubricating in its cold start condition isn't it?
That's what my point is.
A cold viscous 0w is not going to make any extra wear in this engine in it's cold start, since the recommended cold viscous grade is 5w.
So a 0w should work equal or better than the 5w grade in the cold start conditions.
And Since we are using a "multi"grade engine oil. The hot viscous 30 along with this 0w(combined to form 0w30) is not going to harm this engine compared to using a cold viscous 10w instead of the "manufacturer recommended' grade of 5w-30.
Hence recommended to stick on to this 5w30 or even 0w30 if fuel efficiency has more priority.
Regards,