Participating Walmart locations offer $5 off one Castrol Edge Motor Oil 5-Quart Jug or five Castrol Edge Motor Oil 1-Quart Jugs via this printable coupon. (Select "Automotive" from the "Categories" drop-down menu and see it in the first row.) That ties last year's mention as the best deal we've seen on Castrol Edge motor oil. Coupon expires August 31.
Note: You'll need to install Coupons.com software to print this coupon.