Sure it can cause problems like your battery not charging or whatnot, but I was refering to internal engine damage.

I have heard that running the recommended 5w-20 is too thin however, like mentioned, especially in hotter states.

We run 5w-20 in all of the vehicles that come into the shop, and have not had an engine failure yet, but then again, we are in Alaska, so it's the more ideal oil for the conditions.