Since I had no local source for Power Cool, I purchased 12 gallons (concentrated) at W W Williams in Montgomery. No, I didn't drive to Montgomery just to get the antifreeze, I was already there for other reasons. The Prevost Maintenance manual says the bus holds 24 gallons, so I should be safe although I don't think it will take that much. The manager at Williams said Power Cool Plus(PCP) is all they stock and all they have used now for 8 years. He said they use it in all DD applications including RV's and have never had a problem of any kind. They had 260 gallons in stock. Similar ELC's were about $26 a gallon at my local auto stores, so I feel good that I got the original PCP for $17 a gallon. Now if I just had someone to flush the system multiple times in preparation for the switch over!