I have a 2009 Avalon limited and use Castrol Edge full synthetic. Castrol is the best synthetic out there...they claim their oil has 8X the lubrication as Mobil 1.
I buy the Castrol Edge at Walmart for $26 for 5 qts. The Avalon takes 6.4 quarts so you need to buy 10 quarts for the extra needed per oil change. The additional 5 qts will give you 3 1/2 changes.
I go to my local Goodyear and they do the change using my oil. The last change was about $20...they provided the filter and labor. Just ask them what their cheapest oil change is...generally about $26..then ask them to deduct their oil value...usually comes out about $20. This way you get a full syn change for about $55 with the best oil you can get.
Recommend you change the full synthetic at about 5,000 miles...even though the Castrol advertising say it will go much longer.
Oil is the best thing you can do for your engine.
I am not a Castrol seller...do the internet checking yourself to see how good this stuff is. Better mileage, cleaner engine, longer engine life,etc.

Dean