>Actually, it has quite a lot to do with it. The intended
>airflow is for clean air (from inside the air filter) to ENTER
>through the filler neck, replacing the crankcase vapors drawn
>OUT by the PCV - Positive Crankcase Ventilation. Earlier cars
>with a road-draft tube didn't need the clean air
>entry point on the filler neck, as the crankcase vapors were
>merely vented towards the road under the car, clean air never
>entered the crankcase.
The earlier cars DID vent air in at the same place. If you will note, the
chrome cap has 4 "scallops". Each one is a wide hole allowing air into the
engine. Now, I will grant you that the air did not come from inside the
air cleaners, so it is not as "clean". Also, I don't know, but think that
the road-draft tube might have had sunction on it from the air under the
car travelling past it. It might not be as much suction as through a PCV
valve. But, there was some suction. So, is the main difference simply
that the air going through the older style cap is not cleaned allowing
particles to get into the oil?
Jay
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