my cousin works in a toyota casa....di raw talaga advisable engine flush...yun emphasize sa kanila during training / seminars.....it something to do with the components in the flush na ma corrode lalo interanals.......

pati putting air hose to flush.....may kasamang water droplets ang compressor ...then punta sa engine....

let it drip to the final drop...replace...oil filter.....and NO additives like STp...