[supervisor1886]

while the engine is idiling at operating temperature pull the crank case breather tube from the top of the intake manifold. if there is very little smoke or, even better, no smoke coming out then you have scored a great find; however a good ammount of smoke does not mean that the engine will not serve well on a daily basis, just be aware that the engine is showing it's age (this will probably be the case at 174K). also a little bit of oil may come out too, especially if there is no splash shield over the cam shaft. you can see the splash shield, or lack there of, through the oil fill hole.

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Did you mean it is supposed show the amount of blow by in the engine?
I assumed that. i have seen some severe cases on 6 bangers by Volvo when the copression was so low with the oil and comp rings failind that the crank case was so pressurized that it would burp oil into the air cleaner through the PCV hose.

Also the emissions test is a great way to tell the condition of the engine, even if people try to play with timing.