Yesterday while leaving work I noticed a huge cloud of smoke behind me. I thought maybe I was seeing things so I watched closely as I started my tahoe this morning and sure enough it looked like a damn mosquito sprayer. Blue-white smoke pouring out of the exhaust, but stops after a minute or so and it's fine after. Evidently it's an internal oil leak or something. If you know what this is please enlighten me. It's a 2009 Tahoe w/5.3 and 86,000 miles.

 

Bad valve stem seal or broken valve guide would be my first guess. Definitely sounds like a head problem. Pull the plugs and find the black, oily one. That is your problem cylinder.

 

PCV issue?? Look thru the throttle body and see if the intake is full of oil. Other than that, if it only smokes after it has sat for a while, I agree with Swift's prognosis of bad valve stem seal(s).

 

Valve stem seals. Although you may also have problems with the valve guides as well.

 

Noticed while driving that my oil pressure is really low, like under 40. Constantly fluctuating between 20 and 40.