So I'm switching from Valvoline blue 15W40 to Mobil 1 5w40.
Any thoughts of when to change the oil the first time through? I figure since there is almost a quart of old gunk in there I may want to shoot for a shorter interval than I normally would consider with the synthetic. Or is contamination not an issue with the mobile 1?

-nB

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'83 300D Turbo
Current: ???K mi - 19.2mpg -> 17.4mpg -> 22.9mpg ---> ODO Died
bought at: 233.8K mi - 10MPG For $1.00
3.5 cylinders work: 320 320 100 340 280
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