Bought this with 102K and the dealer service advisor strongly suggested standard Toyota oil(non synthetic) every 5K miles. He didn't recommend synthetic. My first change only cost me $46 parts and labor so I wanted to know if I should stay on this track or make the switch to synthetic now? This is a DD vehicle. Also, any benefit to adding small amount of Seafoam or Mystery oil before next change to clean out any old accumulated sludge? Thanks.