Oil gallery for the gearbox is presurized from a t-fitting from the oil pressure switch at the engine, therefore, if you have oil in your engine, then your covered. The oil gallery could be clogged, but doubtful. The TRD S/C as helical cut gears that have a lot of play in them. The noise comes as a standard option at no extra charge. You should be running 5W-30, synthetic is best.
You don't want to end up like this
