Just a bit more info.
Is this a newer engine?
Has it had its first
oil change?
Did this just start to happen or has this been going on for a while?
Ring seating is a primary reason there is blowby on new engines.
For those not so new, a simple compression test if a leak down is not available may give you some indication of which cylinder may have a bit to much wear or stuck ring(s).
Additionally, a plug check may also lead you to a cylinder that is challenged.
