Walmart offers Mobil 1 Synthetic 5-Quart Motor Oil or Mobil Super 5-Quart Oil in 23 varieties from $7.17 after this mail-in rebate. (The starting price and rebate amount vary based on the type of oil you buy. Amazon offers many of these items for the same price for Prime members.) Opt for in-store pickup to avoid the $4.97 shipping fee. That's $5 under our August mention and the lowest price we've seen for any Mobil 5-quart oil. Rebate ends May 31.

Note: Although Walmart is not specified on the rebate, customer service states that this list is not all-inclusive, as it reads "some participating retailers".