i've burned up a turbo already once this year due to a cracked oil pickup tube and got to experience all of these joys first hand already... can't wait to do it again.
When i'm putting the stock exhaust back on i'll be looking for blowby. may as well pop the intercooler off then, although I'd assume rear seals since i'm seeing smoke.
Any thoughts as to why it may be intermittent? Could it be related to the lean nature of closed loop?