I have an 07 tundra w/ 22k miles on it.
I have run 0w20 amsoil in it with some cold start knocking. This oil is performing VERY well for light duty use. Actually at 5k miles, the oil looks almost virgin in wear metal content. This is not my truck, someoene elses. Mine IMO, didn't fair as good, as it sees mainly heavy towing use.
Current fill is ASL 5w30 and the truck is much much quieter, and no cold start knock at all. Lost some city mpg, but hiway is stellar at 19-20 mpg. If amsoil recomended this oil for the 5.7, i would continue it's use. But the only 30w they recomend, is the SSO 0w30 which has proven to be one of the best oils you can buy. This will probably be put in next fill.
These are the 100% synthetic oils and are a little expensive when not used for extended oil change intervals. My OCI are 1 yr/13k miles whichever comes first.
Amsoil's XL5W20 is a great choice and can be had for $5.00 a qt. P.C. price.
But for 5k intervals and light duty use, IMO a cheap synthetic is a good choice.
I would definately recomend synthetic though.
Oh, and i recomend an early change at about 2000 miles or so.