Toyota is not saying it is bad to use synthetic. This is their currentstatement on their Customer Help web site which has not changed:
"If you decide to use synthetic oil for the engine, it is best not to switch until the first scheduled oil change. Synthetic oil should meet the specifications provided in your Owner's Manual. If synthetic oil is used, Toyota recommends that you continue to observe the oil change intervals laid forth in the Scheduled Maintenance Guide. Also, once synthetic oil is used, you should keep using it and not switch back and forth with natural petroleum-based oil".
Perhaps if more people were to write to them asking why you should not switch between conventional and synthetic oils, they would change their position, or explain their stand.
