I had that trouble with my 84 500sec when I first got it. I put rotella in it. I switched to mobil one 10w30 and it went away. Thinking it was cleaned out I went back to rotella and it came back. Then I switched to mobil one permanently. I ran the mobil one a bit longer and the money thing worked out about equal.

Tom W

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.