I keep telling my friends with gassers to replace the timing chain every 125-130 miles.I do it regularly on all my cars and I've never had one break. My ex mechanic on the other hand had a beautiful S500 (w140) with 135,000 on it. I told him to change the chain and he laughed. Four days later I got a call asking if I could drive him home because his timing chain broke!
I tried not to laugh.....it was hard though
