Originally Posted by loneryder
I may let her go 2yrs on this OC.
It's true that Toyota 3.5 V6's are very, very good engines. However, like all modern engines, they use low tension piston rings, a timing chain and variable valve timing.
The oil change is the only way to remove combustion byproducts such as soot, and the evaporates from the fuel that bypasses the rings. Low tension rings do, at times, tend to let more "sneak" by. Furthermore, the rings are more likely to stick in the pistons when carbon builds up.
The right solution is to use a quality oil and change it regularly. I don't suggest 15,000 mile oil changes on modern engines. As the engines are just too expensive to risk. Examples of early failures abound, including Toyota engines. Good Maintenance is the solution to avoiding known issues.
Remember that soot and particulates are hard on timing chains, especially with very thin oils.