I performed my first oil change on the 2011 Sienna today. For those who have changed the oil on the 2007 or newer Tundra, its pretty much the same.
The 2011 Sienna manual says that it should only use 0W20. I picked some up from my closest Toyota (1.5hrs away). It was a good price at $5.65 CDN per litre. It does not say on the bottle if it is synthetic or not. It must be at least semi-synthetic. If it is full synthetic like the invoice says it is the cheapest price around (In Canada anyway). I think I might start using it in my Tundra.
You need a 14mm socket, the 65mm oil wrench for tools. The engine uses 6.1 litres of 0w20 and I purchased a few filters from Toyota as well.
The oil change interval for the 2011 is an oil change at 8000km and 16000km and after that only every 16000km.