There are a lot more factors to gear oil than just brand and weight. Many brands do not label all of the additives and the chemistry behind them. Gear oil that is not specified by your manufacturer can have detrimental effects on the internals of the tranny due to unknown additives. Stick with Toyota recommended tranny fluid and you will have no issues, plain and simple.
http://cloud.tapatalk.com/s/5871bbc6...nsaxle_oil.pdf