March is the first anniversary of owning my '03 Corolla. Toyota says the tranny does not have to be changed, I did it anyway - an over doer like most of us. Anyway was I glad it did! The old ATF smelled terrible while being drained. When I put new Toyota Type IV in, it seemed to shift smoother. Someone on this board said for "cheap insurance - change all fluids once a year". IMHO, that's very good advice.