For Prime members only, Amazon offers the Castrol GTX Magnatec 5W-20 Full Synthetic Motor Oil 5-Quart Jug for $15.90 with free shipping. (Walmart charges the same via pickup.) That's tied with last week's mention and the lowest price we could find for this volume by $14.

Note: This item is temporarily out of stock but can be ordered at this price and will ship when available.