If break-in oil still exists, I believe it is made with higher amounts of ZDDP ("zinc") than you find in regular motor oil. This additive is an antiscuff agent that bonds to metal and heals the metal any time there is metal-to-metal contact. I don't think manufacturers use it any more.

Our resident lubrication expert where I work recommends dumping the initial oil charge as soon as the new car is home to get rid of the manufacturing grit found in a new engine. A bit extreme, but there is some truth to his thinking.

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95 E320 Cabriolet, 169K