Walmart offers five quarts of Havoline Motor Oil in 6 varieties from $8.24 after this mail-in rebate. (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 a savings of at least $5 compared to what you'd pay at other stores. You can choose from 1-quart and 5-quart options, but the total must be at least five quarts. Rebate expires April 30.