Blue smoke comes out the exhaust pipe after going 65-80 mph when you slow

SOURCE: My 69 Chevy Impala is

try replacing the valve cover gaskets

SOURCE: 93 Cavalier runs real rough

sounds like you left something out. check to see if you plugged in all the sensors and plugs, then check for any vacuum lines that were not replaced or may have been broken

SOURCE: Upon starting avalanche blue, white smoke comes

Take that truck into the dealer and have them repair it under the powertrain warranty. 2007 offered a 5 year/100,000 mile warranty.

The smoke on startup is the result of oil getting past the valves.

SOURCE: change oil light came on, car had oil change 1000

get oil pressure test done and check for codes in PCM

SOURCE: smoke when idiling

U need to replace your valve stem seals.