2009 Tahoe LTZ 5.3L, 135K: Blue exhaust on start up
 

We bought this new in 2009. It has had every oil change required, using Valvoline 5W30 synthetic. Recently, it started producing blue exhaust smoke on start up. It does not smoke after warm up, and uses no oil. The diagnostics do not indicate any issues. Ideas?
Thanks!

Just a little bit of oil from the valve stem seals/piston and rings, burning off a little oil on startup. Nothing to worry about IMO. I'd just keep doing what you are doing, like chaningthe oil on time and not worry. I like Valvoline synthetic motor oil myself. Used to use Royal Purple, but it doesn't meet the Dexos standard GM set for GDI motors, and frankly I think its overpriced now that I am older and wiser (I hope).

Welcome to the forum. Another possibility is worn valve guides. I don't normally believe in chemicals for fixing mechanical problems but in old engines, I have had good luck using something called Restore. It's an oil additive.

I would second the valve steam seals... every once an a while I might get a bit of blue on start up after the vehicle has sat for a few days, particularly when cold, but otherwise no oil consumption...

Keep doing what you're doing, no need to fix. New valve stem seals will be costly. Smoke just at first start up and essentially no oil consumption is no need to worry. Just check oil level once per month, and change like you've been doing.