i take it that this 'Vulcan' engine is the 24valve V6 Ford engine and not the SHO Yamaha designed engine-right? anyways, since its a DOHC engine & not a pushrod V6, itll beat up on ht eoil a little more so than otherwise and i would have NO issues running say the german castrol syntec 0w-30 or perhaps even M1 0w-40.
OTOH, most new car owners that have engines requiring a 5w-20 oil are petrified of having their warranties voided out for using a(n) Xw-40 oil and since i dont know you, ill assume you too are worried as well. (mind you theres nothing wrong with this. a car is a BIG purchase)
For these people id recommend using either a low syn. 0w-30 oil like, M1 0w-30 or if you can find it, M1 0w-20. both would be fine for your app but, in hot southern climates (like i live in.) an ACEA A3 oil IMHO, is a must for one to use. Again, just MHO.
In short, welcome to our little corner of the web, grab a quart of oil, gently swish around and sniff....
ps. oh yeah, definetely use a syn oil for sure. Or, you can use the Motorcraft 5w-20 or Conoco hydroclear 5w-20 oil and go 3500 or so miles on it too.