This is true. Shortly after Ford introduced the 5W20 requirement on most engines in 2001, they also recommended backfitting many cars with the thinner oil as you can see from the TSB.
Something significant about this is that Ford stepped up the performance level of the new oil to meet the next set of industry specs (API and ILSAC) even the requirement went into effect. This ment that they had to improve the blending stocks enough to be able to call it a "synthetic blend". They also made sure that the additive package was very healthy. It was a few years before their 5W30 had the base stock improvements to be able to call it "synthetic blend". Doing so, and from thier testing, they felt that the new oil was superior to the 5W30 and that it would provide just as much protection.
There are those that argue that Ford only did this to improve their CAFE (corporate average fuel economy) ratings. I won't enter that debate. It is significant that the 5W20 has proven to be an excellent oil.
I did not make the change for a few reasons. First, I had my doubts about how good it was (now proven to be unfounded). Second, I already had a lot of miles on my engine and didn't want to risk changing. Third, I noticed that the revised chart showed that the Focus SVT should use 5W30, and felt that the Contour SVT was probably used just about as hard.
I should note that I use 5W20 in my Escape.
