Engine burning oil after rebuild

[CM870]

Hi guys new guy here I recently bought 06 T600 isx cm870 the previous owner said it had a in frame done with papers to prove it also the truck had a turbo replaced when I was looking around the truck did not burn any oil recently it’s started burning oil not to bad but still does it only drip down the passenger side I’m guessing into exhaust manifold drips and burns only while idling once I take off I get a cloud of smoke and then it’s gone no more burned oil smell but once I stop let it idle and take off again same thing happening checked the turbo and everything is clean no oil anyone else have this problem please help or did MHC did a shitty rebuild thanks