I've used 20W-50 Valvoline semi-synthetic since day one back in Jan 2002. Never had a lick of trouble with it. I prefer thicker oil, especially once an engine has some miles on it and the tolerances get a bit looser. Since my warranty is long over, I do not care what the manual or ford say about the issue. 20W-50 until the end for me.
Unless you live in some area where the temps get below about -20, you will not have a problem. You might get a "little" better mileage on 5W-30, but I cannot stand pouring colored water into my engine. And thats what 5W-30 looks like to me.
Being I live in Oklahoma. it does get down in the teens during the winter. Never heard a peep out of my engine in the morning. Also I usually go out and start it. Lock the doors, then come back inside and finish getting ready for work. Then when I do go out some 8 to 10 minutes later, the heater is nice and comfy.
I also use the same oil in my wifes 98 Taurus 3.0 DOHC, and have for over 200,000 miles. Not a problem or even a hint of a problem. I also use 20W-50 in both our motorcycles, and have used 20W-50 in every vehicle I have ever owned for over 32 years. I've never had to rebuild a motor yet, and have put 240,000 on a 1980 Datsun 280ZX, 200,000 (so far) on a 98 Taurus 3.0 DOHC, 104,000 on my 98 3.0 automatic Ranger, 180,000 on a 1978 Pontiac Firebird Trans-Am, etc.
20W-50 has never caused me any problems, and I have always lived in areas where the winter time temps get down in the teens or single digits. Hence, I will forever more, use 20W-50 in all my vehicles.
Again, y'all can keep your colored water.
PS, I do my own oil changes because not a one of the "quickie" shops around here even bother to have 10W-40 anymore. Most of them go up to 10W-30, and that will never see time in any vehicle I own. I usually take it for 30 minute drive to get nice and hot. Pull the plug and filter and let it sit for about 30 minutes while I eat a sammich. New filter, refill and I'm on the way.