Nissan Repair: 2002 Nissan Altima, 2002 nissan altima, infiniti g35 sedan

Question
Hey there, here is my situation.
I test drove a 2002 Nissan Altima that i am thinking of purchasing, however, there are a couple issues i need help with.  First of all, the exhaust pipe has black soot in it, and i always thought that meant that it was burning oil....is this true?  Also, the service engine soon light will not go out, but they say it is nothing.  The car is in PERFECT shape other then that tho.  should i be concerned?  I am also looking at an '03 Infiniti G35 sedan with 125,000 Km.  Is this too many, or can it still have a long life after that?  thanks for your time.
Drew

Answer
Drew,

Both cars are fine and the black soot is just part of the fuel injection byproduct.  Under cold enrichment you develop the black soot in the pipe.  Now, if it were excessive I would have a problem.  But, check out the Infiniti and others and you will find the same black stuff on the exhaust pipe.  I wouuld love the Infiniti and the miles are not too much.  The car has the potential to go 250,000 miles before deep engine work.