Found a reliable source of Castrol Oil
 

I have a hard time buying the factory-spec oil for my 5.0L because the local dealers won't sell it in quarts (they claim they only have drums), and eBay and Amazon are hit or miss for having it available. Since I also have a Range Rover, and they used the same 5.0L engine, this 3rd party parts seller has the oil in a kit with the filter.

It works out to about $12.50 a quart when you consider they include the filter and drain plug, which isn't too bad a price, but the key is that they are easy and reliable for ordering:

http://www.roverparts.com/Parts/OCK150

Hope this helps someone else.

Thank You it helped

Thanks. I have a 5 qt jug of Pennzoil plus 3 qts that I got from Walmart (hit or miss) plus a Mahle filter that I got from Rockauto so I'm going to take my car to a local gas station for labor only and NYS inspection. I finally reset my service indicator (it took me around 20+ tries -- you have to be very fast).