Drove my 1990 300E to 175K on original chain. I just had the chain replaced on my 1992 300E at 214K. I bought the '92 at 100K and have run it on Mobil 1 with changes at 3 to 5K, 95% long Interstate trips.

There was no noise, but thought it should be done. If you are changing the
oil and filter regularly, why worry about it?

Steve