It seems to me that three things make an oil wear out. Contamination, if you're running rich or have bad rings, valve guides some higher detergent oils may be better. High temps may break down the bulk modulus, so lubrication is lost & chemically change or vaporize the oil. Oil worn out or broken down, rarely happens, unless because of first two.
Deisel oil may help on contamination & heat. Synthetics definely help on the heat. I think Porsche reccomends Synthetic in all new models. Unless it was one of these I wouldn't run Syntheic in NA except for extreme conditions (racing aircooled motor). To me it seems like Castroil, holds up good from vaporization but thins out more at high temps than Mobil 1.
drew1
|