I bought a g35 and unknowingly 4000 miles later the oil pan went empty and resulted in a rod knock. Replaced engine that has 80k miles and is blowing white smoke.
It's not noticeable really at idle, unless I start revving the engine to high rpms. It doesn't come out thick. At one point the smoke almost was darker.
Now the engine has been sitting in a junkyard for a while probably. My dad said the catalytic converters were very bad but he soaked them in bleach.
Also, I noticed a loss of coolant but I didn't see any coolant in the oil and the radiator doesn't bubble. It hasn't overheated and the engine doesn't lack power. when driving the car kind of smells like I'm behind a Mack truck or something.

Just trying to describe my issue the best I can. I don't see any smoke at all if I just drive normal but if I bring the car to high rpms smoke will come out, but not thick.

Does this sound like a head gasket issue, could it possibly be something else?

 

If you are losing coolant, I bet it's going into the cylinder and getting burned off. Do a compression check and see if all the cylinders are within 10% of each other

 

Compression check. Could also be something as simple as replacing the PCV valve. Those can cause smoke when revving with no load, or WOT pulls.