Walmart offers Mobil 1 Synthetic 5-Quart Motor Oil or Mobil Super 5-Quart Oil in several varieties from $10.47 after this mail-in rebate. (The starting price and rebate amount vary based on the type of oil you buy.) Opt for in-store pickup to avoid the $5.97 shipping charge. Rebate ends October 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".