quote:
Originally posted by Ted Kublin:
Bob,
You are simply wrong about the Noack volatility - it corrolates very well with oil consumption in actual use. Even though the sump temps may not be close to the flash point, there are areas of the engine, like the upper cylinder walls and valvetrain, where the oil is locally heated to a very high temp.
TooSlick
I think you're falling into the same trap as many I see Ted. Let's look at this in a couple of ways and maybe you'll understand how you are not seeing the whole picture on this volotility thing.
First let me state that it obviously has some merit to look at but it is not the all to end all when looking at the #'s.
The volatility of an engine oil is measured using ASTM test method D5800 (NOACK Volatility % Evaporation Loss (ASTM D-5800)). A known weight of oil is heated to 250°C in a special chamber and held at that temperature for one hour.Now let me stop here for a sec.. 250C= about 482F give or take and just where in the engine is the oil going to see those kind of temps for that duration of time? I doubt the valve train does. I stated that the oil may be exposed to some high temps but then it passes back to the sump and if your oil is maintaining this type of temp, then that engine has more problems than what the oil is producing. Anyway, Air is introduced into the chamber and maintained at a constant flow rate under slight vacuum. After one hour, the amount of oil remaining in the chamber is weighed again. The percentage of oil lost is determined by comparing the remaining weight of oil with the original weight of oil.
Another important but yet not normally available test on tech data sheets for determining oils capability of oil resisting oil gelling/sludge which is what happens when you start burning off oil through the means which is measured by noak is Oxidation resisitance.
Oxidation resistance is the ability of an oil to resist the direct and indirect attack of oxygen during engine operation. The way in which an oil is formulated determines its ability to resist oxidation. Strong oxidation begins to occur rapidly after the antioxidant additive in the engine oil is exhausted, so the type and amount of antioxidant in the oil determines how long oxidation will be resisted.
This is another factor that plays on oils ability to maintain it's ability to stay in grade among other things.
Point I'm making here is, Don't push one aspect of an oil as the "selling point" of that oil as it only plays one little part and means nothing just by itself.
As for being hard pressed on extending oil drains with a mineral based oil, It can be and is being done and especially now with the newer GF-3 oils, this aspect is not as much of an issue as you would like to believe because no oil endures that much heat for that long in an engine.Not to mention, To extend the drains as Amsoil does it, your constantly refreshing the additives and base oil with new make up oil and this can be done with any decent oil. I'm not saying the amsoil isn't a quality oil but I try very hard not to instill the wrong idea that just because ONE thing quoted on a techdata sheet is good, then that oil's the one I'd choose based on that one item. Those are benched out as an extreme and dosen't represent the norm, but a way to push the oils limits for that one test.
