I got 66K on my '04.

 

I had it done in dec '06 at 78k miles - cost was $583 - and that was for only the 4 pass side cylinders. I didn't like the price tag, but was afraid I was about to have a larger failure. About the oil -yes the manual says "preferred" is 5w30 for 4.7L, but also says 10w30 for higher temp climates. I commute in the urban south and the engine seems to like the higher viscosity.

I'd experiment with a higher viscosity or STP oil additive first.