5w30 vs. 5w40

[CTScott]

Originally Posted by BLOODY_STONE

you mean by "cost a little bit of fuel economy" that i lose some of the engine power too?

Correct. It would likely not be a noticeable amount.

As far as preserving your engine goes in a hot climate, ensuring that the cooling system always functions is probably going to extend the engine life more than running a slightly more heat tolerant oil. I don't think that I have ever heard of one of our engines being destroyed by oil choice, but have seen a few cases of over heating doing significant damage.

I myself am crazy with the whole oil thing, having been always instructed by my father to never go more than 3000 miles between oil changes, but I know that my continued practice of doing oil changes ever 3000 - 4000 miles is hurting my wallet more than helping my cars.