2010 Toyota Avalon Owners Manual - Page 459
2010 Toyota Avalon Manual
Page 459 highlights
6 -1 . Spe c ific a t ions Fue l infor m at ion Your vehicle must use only unleaded gasoline. 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.