you are going the HAVE to have some clearance.
if you dont have clearance....... then you have nowhere for oil to go around the shaft to lube it.
Not sure what turbo you are running or nothing but i would think that .005 is suffecient to get good lube oil around it when it is spinnin up there.
Wherever you bought your turbo from should have/might have runout specs on the turbo you have.
Lance
What does runout have to do with oil circulation and clearance?
Runout is how much the shaft is bent basically.