Timing chain guides can last 300-400 miles if you change the tensioner regularly.

If your symptom is primarily rattle at start that fades that's the initial loose chain symptom and you can catch or before any damage occurs.

I didn't see your year to know if M62 or N62. It's uncommon for N62 to have guide trouble but I've seen it.

You can use a flexible snake camera to look at the chain/guides through the oil fill port. If the plastic has started to disintegrate don't run the engine, tow it to where you'll fix it

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)