I finall y got the engine running in my 1995 bonneville. I did LIM gasket and installed a heat shield and reduce diameter stove pipe. IT started right up and then starts smoking bad after about 5 minutes.I assumed this is from all the oil residue in the exhaust from the previous engine. There was some oil actually dripping out the exhaust before the engine swap. How long will it take to clear this up or is there something I can do to clean it out of the exhaust? I hope this is all it is? ANy suggestions would be greatly appreciated... THanks

This is typical. Installing many new gaskets and doing major work on an engine typically results in some oils and coolant on areas where it would normally not be found and where it would burn off.

10 minutes or so most of it should be clear.

Agreed!

Plus, if there was quite a bit of oil in the exhaust from before, it may take a little longer for it all to burn out of there, but it still should taper off pretty quickly.