From another thread. Ford, like Honda, recommends 5W20 for fuel economy, where they've stated so in their TSBs regarding it's use. Like Honda they use also use heavier oils outside of the US. This is common knowledge now in this forum.
The question is still one of 'why are other oils recommended if 5W20 is supposed to provide superior protection ?',
and 'why is 5W20 only recommended for improved fuel economy if 5W20 is supposed to provide superior protection ?',
and 'why do so few high peformance vehicles, including turbo charged models, not use 5W20 if it is supposed to provide superior protection ?',
and 'why doesn't Honda and Ford state that 5W20 provides superior protection if it is supposed to provide superior protection ?'.
Because it doesn't, it provides better fuel economy with adequate protection.
"A lot of (most ?) police departments don't seem to keep cars beyond 100k miles as it's considered a safety issue. 5W20 works fine, use it with no concern, but the question for those who do plan on keeping their vehicles for as long as possible is 'what oil provides the maximum engine life', not which one provides adequate life or the best fuel mileage. It's interesting that Ford held closed door sessions with police departments when discussing 5w20. I guess it's to continue keeping it a secret that 5w20 provides the best protection possible, as Ford certainly doesn't want that to get out.
http://www.pfmmag.com/MarchApril2004/MarchApril04fordPEB.htm
Ford Police Advisory Board
By Ed Sanow
Ford’s Police Advisory Board (PAB) ......
5W-20 Oil
Extended discussions were held, both in closed PAB sessions and in open sessions with Ford Fleet, on the use of 5W-20 oil in the 4.6L CVPI engine."