220 is fine. I say, if it ain't broke, don't fix it.
As noted above, the Turbo covers are used to stop leaks more than lower temperature. You could try those heat sheets and a cool collar, but don't show them to any engineer friends.
An external cooler, with thermostat, oil lines, cooler, shroud and fan, can easily run you over a thousand dollars.
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Jack Olsen
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