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pour point =/= cold flow temp Posted by TML [Email]  (#2212)  [Profile/Gallery]
(more from TML) on Thu, 27 Oct 2011 08:38:59
In Reply to: Re: Actually, Simon S, Wed, 26 Oct 2011 21:56:30 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Not meaning to cause offense, but this is a good example of pseudo science. You've taken one spec that doesn't mean what you imply it does, from one brand of oil, and made a sweeping generalization that has no justification. You are quoting the spec for the pout point; referring to this number as "cold flow temp" is flat out wrong. Pour point is of very little real world significance. At the pour point, the oil is VERY thick; basically if it moves at all, that's when it's reached the pour point. It should not be considered a "cold flow temperature", as no flowing will be taking place. Just because there is only a 6degF difference at the pour point does not imply that there will be only a 6degF difference at the point the oil becomes actually useful. At a real world temperature of say -30F, the 0W oil will be a lot thinner than the 10W oil. This is why the pour point is not a determining factor for the grade. The CCS and MRV viscosity tests are what determines the xW number. 0W and 10W oils are tested at different temperatures (-35C and -25C, I think). I will admit that in the particular case of Amsoil 10W30, it does seem to have quite a low viscosity at -25C, but this is not typical in other brands. All it really tells you is that there's less difference in grades in Amsoil oils than in other brands, and that MAYBE 10W30 Amsoil is almost as good for cold weather as Amsoil 0W30, but it's just speculation because you don't have the measurements that would actually tell you that. If you try to extrapolate that out to other brands, it becomes demonstrably false. For example, if you compare Esso Extra XD-3 0W40 with 10W40, you see that the 0W30 CCS viscosity at -35C is actually lower than 10W30 CCS viscosity at -25C. They have these grading systems for a reason, and the advent of synthetic oils does not change that.
posted by 24.246.55...
, Mon, 24 Oct 2011 17:29:07, Tue, 25 Oct 2011 17:59:33, Thu, 27 Oct 2011 08:38:59 <-- Viewing This Message
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