[CrashNburn]

according to my owners manual, ford said to use the 5w20 all the time. your already running synthetic! good idea, and one of my favorite brands lol) so i would just keep up your regular maintenance. if its mostly highway, dont worry about the temperature. if its all stop and go at 100deg then i would just keep an eye on the temp guage.

 

[CrashNburn]

to add to it, i had an 01 windstar and put 200,000km on it and did oil changes of 5W20 regular oil and filters. and never had a problem. 5w20 is expensive, and hard to find at a gas station in the middle of the night, but it seems to work great.