Oil Specification for 2009 Toyota Venza - Will 10W-30 give longer engine life than 5W-20?

Toyota specifies 5W-20 or even 0W-20 for my new 4 cyl. Venza. These are about the viscosity of water. I suspect that these are specified to provide less friction at start-up and improve the (fleet) mileage numbers slightly. I also suspect that these very light oils do so at the expense of engine life and wear. What do you automotive engineers think about using 10w-30 in this vehicle for all oil changes, even if it means more difficult winter starting. I'll bet that the other oils will result in drastically lowered engine life over the long term and I'd like to keep this car for 200,000 miles. No amateur guesses please.