I got it from AAP close-out for $1.95
I will be using the 15 qt stash for future summer months, beginning next month or so for this yr.
Benefits over conventional oil would be the same for any HM over any conventional...do a search on that, or go to any brand's HM info-page...will give you a good idea what the benefits are.
I personally do believe in HM, 'cause I strongly believe an HM oil (Pennzoil specifically) helped stop a leak/seep/consumption in my Tbird, and it keeps the car running very smoothly. They've been good in my personal situation.