Check with Mobil, this is a known phenomenon. Tests were done about 1970 or so.

Try it yourself, all the varnish will disappear in a dirty engine.

Synthetic base is a "detergent" by structure, not a hydrophobic mineral oil, and will disperse and dissolve considerably more materail than dino oil. Period.

If you don't believe me, go look up the data sheets and recomendations from Mobil or Amsoil.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!