MolaKule
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Stribeck Curve and Wear and ZDDP
- Thread starter MolaKule
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Another paper showed no advantage in wear characteristics when ZDDP was 0.03 or higher:
Development of the Sequence III G Engine Oil Certification Test, Clark et al:
Engine tests were made more severe again. (Over the years the oil ratings have improved but this has always been despite the increase in testing severity. It was III ...D, E, F, and is now III G). The oil inlet temperature was decreased from 155 to 150 C. The test was 80 and is now 100 hours. There were 8 oil level adjustments allowed now there are 5. The inlet engine air temperature was raised from 27 to 35 C. The engine load was increased 25 percent.
Despite all this the current 0W-20 oils were still GF-4 compliant and showed minimal wear characteristics as long as ZDP levels were higher than 0.03 percent. (The SM rated oils I have seen so far have levels of 0.08).
This lecture as presented shows no improvement when ZDDP is over 0.05.
Another paper showed increased wear when high levels of ZDDP were used and we know that other adverse effects may occur such as corrosive wear.
This paper shows the importance of the formulation in regards to wear. Viscosity is not a factor:
Development of the Sequence IV A Valve Train Wear Lubrication Test
art 1, Sagawa et al:
Viscosity data reveals that the more viscous oil did not significantly alter the cam angle of minimum oil film thickness. Of greater importance is the finding that the higher viscosity oil continued to exhibit boundary layer lubrication. (Ergo thicker is not necessarily better).
The effect of engine intake air humidity was significant so that tests are now done with specified humidity conditions.
It was postulated that fuel dilution of oil would elevate cam wear. Fuel dilution of 4.5 percent did not effect wear. (This would have the effect of lowering the viscosity about 1 grade).
aehaas
Development of the Sequence III G Engine Oil Certification Test, Clark et al:
Engine tests were made more severe again. (Over the years the oil ratings have improved but this has always been despite the increase in testing severity. It was III ...D, E, F, and is now III G). The oil inlet temperature was decreased from 155 to 150 C. The test was 80 and is now 100 hours. There were 8 oil level adjustments allowed now there are 5. The inlet engine air temperature was raised from 27 to 35 C. The engine load was increased 25 percent.
Despite all this the current 0W-20 oils were still GF-4 compliant and showed minimal wear characteristics as long as ZDP levels were higher than 0.03 percent. (The SM rated oils I have seen so far have levels of 0.08).
This lecture as presented shows no improvement when ZDDP is over 0.05.
Another paper showed increased wear when high levels of ZDDP were used and we know that other adverse effects may occur such as corrosive wear.
This paper shows the importance of the formulation in regards to wear. Viscosity is not a factor:
Development of the Sequence IV A Valve Train Wear Lubrication Test
art 1, Sagawa et al:Viscosity data reveals that the more viscous oil did not significantly alter the cam angle of minimum oil film thickness. Of greater importance is the finding that the higher viscosity oil continued to exhibit boundary layer lubrication. (Ergo thicker is not necessarily better).
The effect of engine intake air humidity was significant so that tests are now done with specified humidity conditions.
It was postulated that fuel dilution of oil would elevate cam wear. Fuel dilution of 4.5 percent did not effect wear. (This would have the effect of lowering the viscosity about 1 grade).
aehaas
- Status
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