Found this and figured I'd share in-case anyone else was interested.
K-Mart has PP on sale for $4.50 a quart. Buy 15 of them (67.50), and you can use code DRIVEN for an extra $10 off ($10 off $65 in automotive purchases), making the total $57.50 + tax.
Combine that with Pennzoil's "Buy 5qt get $10 rebate (Limit 2 per household)" promotion going on http://www.pennzoil.com/fallrebate/
, and that brings it down to $2.50+tax a quart.