Unfortunately, my Scion tC isn't in the recommendations, so I'm still stuck with 5w30. I wonder if they forgot about us tC owners?
http://www.scionlife.com/forums/viewtopic.php?t=113779&highlight=oilquote:
In a service bullitin dated 3-29-06, Toyote states: *Toyota motor Corporation manufacturing plants have begun using ILSAC GF-4 engine oil. This engine oil is recommended due to its superiority in terms of fuel economy and engine protection and due to its benifits for both the customer and the environment. ISLACGF-4 can be used in all Toyota and Scion engines. *This recommendation is for 2006-2007 vehicles. *ILSAC GF-4 SAE 5w-20: This oil has been set as the Toyota genuine engine oil, starting in February 2006 for the US. This oil is superior in terms of fuel economy, engine protection, and cold starting performance. *ILSAC GF-4 SAE 0W-20: This oil has even better fuel efficiency and cold starting performance than 5W-20. Initial application for 0W-20 is in the 2006 model year 2AZ-FE engine and will be used in new engines to be developed. *Engines using ILSAC GF-4 SAE 5W-30: AZ series, GR series, JZ series, JZ series, MZ series, NZ series, RZ series, UZ series, VZ series, 1ZZ-FE, 2TR-FE. *Engines using ILSAC GF-4 0W-30 (beginning with 2006 model year): 2AZ-FE Camry, 2AZ-FE Solara, 2AZ-FE highlander, 2AZ-FE RAV4 (ACA#3). **************************** NOTE!!!!!) DO NOT use these oils in engines other than those listed above. These low-viscosity oils cannot maintain lubrication effectiveness in engines with older designs and could result in smoke emissions from the tailpipe and/or unusual engine noise.