I know that moving Air has a lower pressure than static Air. But, there is no Vacuum produced in the Air Filter Inlet (unless there is a significant plugging of the Air Filter).

If there was even a partial Vacuum in the Air Inlet system on an Engine with a Turbo Charger the Oil inside of the Turbocharger will start go past the Seal. At least it does on the Turbos that use a Piston Ring type seal.
I have seen the above happen on Turbocharded Trucks when the Air Filter gets Plugged up.

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84 300D, 82 Volvo 244Gl Diesel