SKF Valve stem seals
If too much oil passes through the lip of the seal, emissions are worsened and coke builds up on the valve, potentially causing the engine to lose power or even fail. If too little oil passes through the lip of the seal, the valve does not receive enough lubrication and will scuff, which ultimately will cause the valve to seize. The ideal metering rate lies between these two extremes.
SKF's high pressure valve stem seals are designed and tested for up to 12 bar pressure which virtually eliminates lip openings during work and minimises blow-by gases.