Hers's something...Oil smoke '90 tqa

[Nick Lawrence]

I start the car in the garage after sitting over night, no oil smoke cloud, then drive about 15 miles.
About 5 hours later I start the car and get a noticeable cloud of blue smoke, drive few miles shut off, restart in 30 minutes, no noticeable cloud. 
My guess is valve stem seals or maybe just very worn guides.  If yes on vavle stem seals any BTDT?

 What might I see with worn turbo seals?

 Engine has 301k miles. Compression test and leak down test doesn't indicate worn rings.  

Nick  central Ohio