Amazon offers the Castrol Edge Full Synthetic 0W-30 Motor Oil 1-Quart Bottle 6-Pack, model no. 06244, for $46.61. Clip the 20% off coupon on the product page to drop the price to $37.29. Plus, Prime members receive free shipping. (Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping adds $9.78.) That's the lowest total in-stock price we could find for this quantity by $28.