What Type of transmission fluid for 2005 Toyota Avalon?

Answer 1

Use only Toyota brand ATF WS fluid from the dealer which is rather expensive but worth it.

There are some well known major brands that say their fluid meets the Toyota specs. I did 3 drains using approximately 4 quarts per drain of the major brand in one afternoon and the transmission didn't shift properly. About a week later did three flushes with the factory fluid and the shifting smoothness returned.