I replaced the plugs in the S420 with good old Bosch Super F 8 DC4s. I would have thought nothing of it but what they replaced were MB logo Beru plugs with 3 electrodes. Are these OE plugs for an M119? Are they platinum? Maybe plugs for an M111/2/3? If I buy plugs for a 95 S420 at the dealership are these the plugs I'll get?

The plugs are marked:

R1 Beru ultra 940
14FGH-8 DTURXO made in France ||| 1.0 |||

Thanks,
Sixto
95 S420
87 300SDL

From all I've read on the M119, they really like only the OE type spark plug. The bosch plug with a single electrode tip is what you're looking for.

Unless designed for a specific engine, I think all of the multi-electrode plugs are junk, which can actually decrease performance in a M119.

How was your car running before the plug change?

Troy
1995 E420 93k

The car was running fine. I have to make sure I don't roll over Civics when I chase down 'vettes

There was a high rpm stumble I traced to a coil wire touching a PS reservoir bracket bolt. Many wires have telltale white spots from arcing so I'm putting in a new set of wires. I'm doing the plugs while it's apart since it's at least 30K on the plugs. On a RT trip from SF to L.A. it got 19.x mpg with the cruise set at [censored] mph. Better than my 91 300SE could manage at that speed.

The French Berus look fine. If I didn't have the Bosch's gapped and ready to go I'm not sure I'd have bothered to replace the Berus based on how they look and perform. I had good luck with Berus (made where?) in a 300SEL 3.5 that had an oil consumption problem. Beru performed when Bosch and Champion were choking on oil. I understand that these Frech 3 electrode plugs might be different.

Thanks,
Sixto
95 S420
87 300SDL