Could a bad valve guide cause.....
 

blue smoke and oil out the exhaust and low oil pressure after coming down off plane or when engine is warm?

Thanks

No. A bad guide will usually show up as a momentary smoke on startup. When coming off of plane there is a high vacuum. This could be sucking oil from a number of places. For example a bad intake gasket or loose rings. The loss of oil pressure would suggest that bearing clearances are getting loose enough that the pump isn't able to keep up. Of course there can be other causes such as excessive oil temps etc...

Let me tell you about a bad valve guide:( I had valve guide come out of the head while driving:eek: :eek: :eek: Then comes a horrifficc noise!!!!! Valve imbedded into piston and cylinder and and about 5K in damage . Anyway I am still hostile about this. Its all my fault but it was still expensive.