Walmart has 1 Quart bottles of Pennzoil Platinum 5W-30 Oil for $3.95
Buy five of those for $19.75, then use the Pennzoil Rebate to get back $10.
The rebate applies for purchases made through September 30, 2018. There is a $10 maximum rebate limit for the offer period July 1, 2018 through September 30, 2018.