I suggest the Mobil 1 at 3K mile change intervals. If too much sludge is dislodged too quickly it may cause screens/oil passages to plug up.

If you decide try the engine flush products, the two I recommend are Rislone and Seafoam (in the crankcase).

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Ray
1998 Mercedes E320, 200K Miles
2001 Acura 3.2TL, 178K Miles
1992 Chevy Astro, 205K Miles