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Re: So I Went To See The Amsoil Man
#2 Feb 1, 2005 6:56 pm |
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centipoise? Cool word! I think, however the correct unit for viscosity as it applies to the discussion here, I.E., the ability of an oil to flow at low temperature is the unit for kinematic viscosity, centistokes, rather than the unit for absolute or dynamic viscosity, centipoise. The two units are related, but not equivalent. Actually, centistokes equal centipoise divided by density. Basically, the kinematic viscosity governs the ease with which a fluid flows, while dynamic (absolute) viscosity is the fluid's ability to resist wear and breakdown (shear). Both measurements are extremely important for your snowblowers (as well as your car). If your oil doesn't flow at low temperature, it will resist being pumped from the oil sump to the engine and your engine won't be protected. If the oil flows easily in the cold, it will quickly reach the engine, but may not be viscous enough to protect moving parts under load and the high temperatures developed when the engine is running. That's why multi grade oils were developed - they flow at low temperature and still protect at high temperature. Probably the best units to look at when considering an oil for your blower is viscosity index (VI). The higher the number, the less difference in viscosity between high and low temperatures. Manufacturers put additives in the oil to raise the VI. Unfortunately, the additives usually shear before the oil, which reduces their effectivity with time. If you're interested in more of this subject, try this link:
http://www.cambridgeapplied.com/news/pdfs/kine_vs_abs.pdf
Warning: Don't try this if you already have more than a couple of beers in you.
If you're interested in less of this subject, I'll end this diatribe now. Sorry for the rambling, but that centipoise word really got me going.
the Hun
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