Toyota Repair: Engine oil, mobil one, oil consumption

Question
I have a 2004 Tundra V8.  Book says 5000 miles oil change but dealer says 3000 because of the heat in Miami, FL.  Who's right?  Also share with me your opinion of Mobil One 5-30W synthetic oil...should I use it and change every 5000?

Answer
Here in CA we also used to recommend oil changes every 3,000 miles but were told to recommend every 5,000 miles because that's what the factory recommendation is, personally I don't agree with this, I think it's too long,
what i find a little ironic is that Toyota considers oil consumption of 1 quart every 1000 miles normal,so it would seem that if your engine holds 5 quarts of oil and you never check your oil in between oil changes, in 5,000 miles your engine could be out of oil and self destruct.
I think your idea of using mobil one is a sound one.