Alright, recent posts say great things about 0w-40 Mobile 1. I've been using 5w-30 for winter and 15W-50 for summer. Is the 0W-40 good for hot summers too? MN summer days range from 50f to 100f. Also, when I went to Pepboys to find 0W-40, they only had 0W-30. I don't know how big a deal that missing 10 is, so I'm asking:

1. Should I even bother with the 0w-40 for summer?
and
2. If so, should I keep looking for 0w-40 or is the 0w-30 close enough?

I think others may wonder this too. Thanks in advance.

BennyM