The timing chain is an absolute MUST DO at 100,000 miles. Don't even THINK about putting that job off, it must be done immediately. New timing chain with NEW TENSIONERS. If the timing chain slips off (old tensioners, broken chain), then you are looking at between $3500 and $6000 worth of work on the car. All hell breaks loose in the engine if the timing chain brakes. So if it hasn't been done, budget the $1500 to get it done and do that right away. Don't wait and do NOT let a mechanic tell you it's OK to wait. That mechanic would be hoping you'll come in there with the blown-up mess and throw him the larger job. I had a guy do that to me. Did I mention that timing chain replacement is a must do?!