Oil leaking around dipstick Chevy 350 what to do to fix?

Make sure tube does not have a crack or hole that is causing the leak. If so, replace tube. If tube checks out ok, and leak appears at base of tube, remove tube. Using a dremel tool, careful not to penetrate all the way thru, make a shallow groove completely around the bottom of the tube. Clean groove of any debris, remove any sharp edges or burs. Then position a smaller diameter O-ring in the groove. Replace dipstick, check for leaks.