ji know its a chevy but just bought an 2003 gmc 2500 lb7 duramax, 270,000 i paid 9500 plus tax southern truck goorgeous shape seemed to run well when test driving no slipping etc. picked it up yesterday and notice an oil spot in my drive way so i check the dipstick and smelled diesel but doesn't appear to be making oil. little bit of white smoke at idle and a few puffs of black when i hammer down. i took it to the used car dealer i got it from and he's taking it to a repair place they use tomorrow. no codes came up when plugged in and the truck still runs really strong. what should i do? any way to tell a injector is bad before hand? thanks everybody.

 

I know nothing about diesels.

 

Bet it's due for a new set of nozzles. Prob has the originals in there.