I'm currently running Motorcraft 5w20 synthetic blend with a Napa Gold (Wix) filter.
The Vulcan isn't very hard on oil at all...the common phrase I've read about it in other peoples oil analysis is the the Vulcan isn't powerful enough to really hurt itself. You'll be fine with pretty much any 5w20 or 5w30.
As far as the synth blends being garbage comment goes, the Motorcraft synthetic blend is an excellent oil. Go read up on it...it shows extremely good results in plenty of analysis results. For $10 for the 5 qt jog, you really can't go wrong with it. IMO is is the best bang-for-the-buck oil you can get.
Since you have a Vulcan, my recommendation would be either 5w20 or 5w30 Motorcraft synthetic blend with a Motorcraft, Purolator PureOne, or a Napa/Wix filter. Everything will cost around $15. Easiest way is to pick up the oil and the filter at Walmart (they have Motorcraft filters) but the Walmart I usually go to never has the filters so I just go to Napa for the filter.
Here's a comparison of used oil analysis on a 2003 Vulcan comparing Pennzoil Platinum, Motorcraft, and Mobil 1
Bob is the Oil Guy link
Sorry about the long post

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