You need to replace your thermostat, which is stuck open.

The Auto-RX will work, and help silence the engine. My lifter tapping was not bad, but now is completely gone. On (very) cold starts there was also a less-noticeable clacking, I assume from the rockers, which went away as the car warmed up. Now it goes away in just a few seconds, and I assume it will be gone completely, just like the lifter noise.

Finally, the normal "roar" of acceleration, which on my car is most noticeable in the 2300 to 2700 rpm range, is now about half as audible as it used to be, and continues to get quieter. (On acceleration above about 2800 rpm, or below 2200 rpm, the engine is extremely quiet - - cannot be heard over wind and tire noise.)

As the oil passages, rings and seals continue to be gently cleaned, the good results should continue.

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2008 E350 4matic / Black/Anthracite

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Gone but not Forgotten:
2001 E430 4matic, 206,xxx miles, Black/Charcoal
1995 E320, 252,xxx miles, Black/Grey
1989 260E, 223,00 miles, Black/Black