There's no safe mileage where your car won't be affected. But you can check to see what the status of it is, there's several youtube videos on how to check it. For $740, you could just drive it until the problem shows up if ever. There's no real good estimate of what percentage actually develop the problem, some say 10% others say more. Even if you get the problem though, you could still drive it for a few thousand miles before one day it leaves you stranded and the car won't start. May people had a theory that not changing the oil was the problem, but MB basically used too soft an alloy in the balance shaft so it wore down. I don't think the evidence is conclusive that using the correct oil and more frequent changes would help with a manufacturing defect. And it's also not clear if every single one was too soft or if there was just a manufacturing problem that was later corrected and cars after that period don't have the problem. Remember correlation does not imply causation.