Use exactly what the manufacture recommends and nothing else.
20 ounces 5w30 small engine oil
30 is a little more viscous (thicker) at operating temperature than 20.
According to the 2002 Ford Windstar Owner Guide the 3.8 liter V6 engine takes ( 5W-20 engine oil )
5W-20 is recommended to ensure proper MDS operation. Unless it's a 6.1l then it needs 0w-40w Mobil-1 only 2.7L uses 5w30 3.5L uses 10w30 5.7L uses 5w20
SAE 20 and 30 are the viscosity [resistance to flow] at about 200 degrees F. SAE 20 will be thinner at engine operating temperature than the SAE30. 5W is the viscosity at about 0 degrees F. Use what the manufacturer recommends. My Camry uses a 5W30 oil. I use the Mobil I 0W30 because it flows better at very low temperatures. See "Bob is the Oil Guy" web site for an excellent discussion of oils and filters.
A windsor 5.0 uses 5w-30 A Coyote 5.0 uses 5w-20
In an emergency, 5w30 would be better.
The 5W-20 is thinner and more viscous. The reason Honda wants you to use it is because it decreases engine friction slightly and they can then claim better mpg. I use 5W20 or 5W30, which ever is cheaper when I buy it. My Odyssey is an 02 with 125,000 miles and still doing fine,
According to your owners manual, it states that you should use 5W30. So, if you wanted the best, you should go with 5W30 Full Synthetic. 5W-20 syntech
I would go with the 20 since it's thicker. 20 is NOT thicker then 30. Yes you can use a 30 weight oil with no problems. 20W oil may be recommended in order to achieve maximum fuel efficiency but, using a 5W30 oil will protect the engine better!
The 2001 and newer Ford Crown Victoria uses ( 5W-20 engine oil )
Above 20 degrees Fahrenheit use 10w30. Below 20 degrees use 5w30.