A lot of people are scared to run a 0w30 oil in summer because they think it's too thin, but if you look closer at the technical specs you might feel a bit more comfortable.
For instance, Castrol SLX 0w30 has a viscosity of 68.5 at 40c, compared to M1 10w30 which is 61.5. So chances are pretty good that at a lower temp of 30-35c, which is a typical summer temp for a lot of areas, these two oils will be pretty much the same thickness, the 0w30 here might even be a tad thicker! It's at the extreme cold where the 0w30 ends up being much thinner than a 10w30. And comparing that same 0w30, it's got a viscosity of 12.1 at 100c, vs M1 10w30 which is 9.8. So which one of those two oils do you think is better in winter AND in summer?
Also, Amsoil's 0w30 is 57.3 at 40c, so if you felt safe running M1 5w30 in summer, then you should feel safe with Amsoil 0w30 since M1 5w30's viscosity at 40c is 53.7.
I think it's all a mental thing, and I suffered from it in the past also. You see the 0w and you immediately think the oil would be thinner than water. But keep in mind, when oil is cold it's always going to be thicker, so a 0w30 oil is still thicker when cold than a 20w50 oil is when hot.