In aircraft piston engines, where tolerances are not as tight, straight mineral oil is used for the first 50 hours or oil consumption has stabilized to ensure proper seting of the rings and bearing surfaces.

In new Mercedes, the machining is so much more exact that they are now factory filled with Mobil 1.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record