2011 Toyota Sienna Owners Manual - Page 834

6-1. Specifications Fuel information You must only use unleaded gasoline in your vehicle. Select octane rating 87 (Research Octane Number 91) or higher. Use of unleaded gasoline with an octane rating lower than 87 may result in engine knocking. Persistent knocking can lead to engine damage. At minimum, the gasoline you use should meet the specifications of ASTM D4814 in the U.S.A. and CGSB3.5-M93 in Canada.