2005 Chevy Suburban blue smoke on start up

Blue smoke from the burning of engine oil in the combustion chamber on start up only is normally indicative of worn valve stem seals. The Valve stem seals control oil from entering the combustion chamber but with wear oil will get past the seals and burn in the cylinder. Typically, leaving the car to stand for a while, and particularly overnight, oil will have time to drain past the deteriorated seals and build up in the cylinder or cylinders with the bad VS seals. Consequently when you start the engine the small amount of engine oil build up in the cylinder burns and you get the noticeable blue smoke emission on start up.

The fix is to replace the valve stem seals.

Ahh, the old Castech head problem.

The LS motors used heads that were made by a company called Castech. Look on your cylinder heads for a three digit number. If you see “706” you have the heads that have bad castings and typically fracture around the head bolts. They actually fracture in other areas too. Are you loosing small amounts of coolant also? You may want to pull the valve covers and make sure you don’t have the milkshake of death in their ( the pink ooze caused from coolant and oil mixing) if not clean up the surfaces and look for cracks. If you search you’ll find GM issued a service bulletin about this issue and recommends replacing the heads.

It could also be seals too. The 4.8/5.3 have been plagued with excessive oil consumption since they came out. My 05 Silverado will consume about a quart every other month. I’ve noticed that the motors that have the cracks typically puff the blue smoke when they sit for over two days. If it’s every time you start it you could have bad valve seals.

This has been my experience with my personal truck as well as many that I’ve worked on through the years

I’m with borne. Check your head casting. I’ve seen them before. Well the after math anyway.