Lubricant-Closed PCV System Relationships Influence Exhaust Emissions

Hydrocarbon and carbon monoxide concentrations in the exhaust of an engine equipped with a closed positive crank-case ventilation (PCV) system were kept at low levels with operation on high-quality motor oil when compared with similar operation on a low-quality motor oil.

The increase in exhaust emissions with the low-quality motor oil resulted from the effects of deposit accumulation in the PCV valve, carburetor venturi, and carburetor throttle body areas.