Asa este . Interesant link-ul tau . Mai ales la pasajul uzura motor .
Antiwear Property Changes
Another change that occurred in passenger car motor oils with GF-2 and GF-3 is a more stringent limit on phosphorus, which is part of the zinc phosphate (ZDDP) antiwear additive. The auto manufacturers are concerned that phosphorus will deposit on surfaces of the catalytic converter and shorten its life.
This is a complicated issue, and the deposits depend on the specific ZDDP chemistry and the finished oil formulation. The industry was unsuccessful in designing an engine test for an oil’s catalytic converter deposit forming tendencies. Therefore, the auto manufacturers set an arbitrary limit for motor oil of 0.1 percent phosphorus.
Antiwear additives are important in the absence of a hydrodynamic film, such as in the valve train. The antiwear additives are activated by frictional heat, which causes them to react with the hot surface and form a chemical barrier to wear.
The mechanism by which phosphorus deposits form on catalytic converter surfaces is not fully understood. It does not correlate directly with oil volatility or oil consumption. On the other hand, if engine wear causes oil consumption to increase, the risk of forming phosphorus deposits in the converter would increase dramatically. It seems that preventing wear and oil consumption should be a priority.
In the past, oil formulators could make a premium product by simply adding more ZDDP. A similar move today would result in an oil formulation that would not support new car warranties.
P.S. Concluzia : ramane cum am discutat !!!!
Ovidiu at 17:27 (GMT 2) on 26 May 2010]