Will I do any harm to my engine if I use Mobil truck&suv oil in a hot climate?(Houston). I have read the manual and it refers to 15-40 as the prefered oil.
Thanks

As long as it has the API spec of CH-4 or CI-4 it should be fine.

That oil would be an excellent choice in my opinion. If you'd like a true group 4 synthetic in 15-40W, I'd look at the Amsoil (AME?).