Here's the link to see if there is a Shell Distributor in your area:

Distributor Locator - United States

One member at BW found it for about $3/Qt in a case quantity, so it's possible to get a great deal on it. But you do have to buy a case, which is fine, since you'll need between 8 and 9 quarts if you also drain the TC, which is easy on the 97.