Probably stackable with this Valvoline rebate for $10 off 5 quarts of Valvoline, bringing cost down to $0.88 / qt. + pre-rebates sales tax.
Form on Team Valvoline site says any 5 quarts, so loose quarts ought to qualify just as well as 5 quart jugs.
"No matter how paranoid you are you're not paranoid enough. Tell the truth. Reach as many people as you can with it. That's your weapon." - Susanne Modeski, aka "Holly" to The Lone Gunmen