For Prime members only, Amazon offers the Shell Rotella T6 5W-40 Synthetic Diesel Motor Oil 1-Gallon Jug, model no. 550019921, for $11.29 with free shipping via the steps below. That's tied with our mention from April and the best price we've seen. (It's the best deal now by $8.) Deal ends December 31. To get this deal:
  1. View the Shell Rotella T6 5W-40 Synthetic Diesel Motor Oil 1-Gallon Jug for $19.16
  2. checkout via Subscribe & Save to cut that to $16.29
  3. redeem this $5 mail-in rebate for a final price of $11.29
Be sure to cancel your subscription once your order ships to avoid being billed for further shipments.