I don't have a W124 300E, CE, TE or W126 300SE, or a SEL, but I do have an M103 in a 93 190E, 2.6 at 149K miles.

When I got it a year ago it leaked about a quart per 1500 miles. My mechanic said it needed a head gasket, but I replaced the upper timing chain cover gasket and the leak stopped. Now I may use 1/2 quart between 3K mile oil changes.

No top end work reported by the only PO (my father) and none needed at this time...X'ing fingers.

Happy in SO CA!

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1993 190E 2.6 135k
1989 Ford Thunderbird SC 5 Spd 79K