98 VW Passat burning oil

My 98 Passat 4 cyclinder turbo burns oil first thing in morning when starting up but then seems to quit. If it sits for several hours or overnight it does it again. It has gotten worse now that it is summer but unsure of any correlation. My mechanic is stumped on the cause unless the turbo seal is leaking. He suggested I go to the dealer but like others they can't be trusted.

This just quite by itself after a few oil changes. Beats me.