There are gravity fed reservoirs of oil that do this (aftermarket). Some Audis in the late 80s/early 90s had watercooled after-run systems....requires a thermocouple and an electrically operated water pump. If you can figure out the water pump, it wouldn't be too hard.

Today's late model Volvos have much cooler turbos than in the 80s and early 90s. The ECU controls boost, and also how long maximum boost will be sustained and then starts spooling it down. Really, who needs 15 seconds of 11psi? You'd be airborn! Thus, at highway speeds, your car runs on lower boost than the old 740 turbos. You can open your hood on a dark night after a long highway run, and the turbo will usually NOT be glowing. Also, key thing - switch to synthetic lubricant.
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David
  Our long national nightmare of peace and prosperity is finally over - The Onion
98 S70 T5SE // Black, misc mods (mostly lighting), red calipers
92 940GLE // Hella Micro DE foglights