I built a Factory Five Cobra using a 2004 4.6L DOHC engine. I had read at the time, 2011, that Ford modular engines were known for lasting more that 200K miles when properly cared for.
Below is an article talking about the 5.4 Triton V8 which is also a member of the modular engine family. The 5.4 DOHC engine in the 2005/2006 is the big brother to the 4.6L is used.
<p>The life expectancy of an engine is one of the most important things I consider when shopping for a new vehicle. I’ve been toying with the idea of getting a new truck, and I’ve been wondering: what is the life expectancy of a Ford 5.4 engine? I did some research: On average, a Ford 5.4 engine...
One difference between the old Windsor and Cleveland engines and the modern modular engine family, the Coyote is one of the newest engines in the modular family, are the manufacturing tolerances and, as mentioned, cylinder coatings. The modular engine family is manufactured with much tighter tolerances, thus the need for thinner oils. Typical oil viscosity used is a 5W20 for street used engines.
For my Mustang build, I chose a 2nd Gen Coyote. I will bet a well cared for modular engine will easily outlast a vintage engine. While the article I reference is not conclusive, it is indicative of what real world owners have experienced. We will continue to disagree, however I have provided a bit of support for my belief, now backup yours.