The '98 S70 was manufactured with 2 different timing tensioners: an automatic/hydraulic (which I have) and a mechanical tensioner. The tensioner or pulleys were not change when my car was last serviced (70K miles), and now I have 110K. To my understanding, unlike the mechanical tensioner, the auto/hydraulic tensioner need only be replaced every other timing belt change. Is this true? What are the chances that the 2 timing idler pulleys will last until next tensioner service- 140K miles?