Asking for Advice Fix 273 or Replace

It might be sucking oil in through the intake ports due to bad intake to head sealing. This can be seen by driving down the road and letting foot off gas. When throttle blades close the vacuum in the intake runners goes up and if there is a sealing problem oil gets sucked in. Blue smoke can be seen coming out of tail pipes but it could burn clean under other conditions.

How do you know its blow by? If you take the breather or oil cap off do you see smoke coming out when engine is running? What makes you think its blow by?