|1st March 2008, 13:01||#31|
Join Date: May 2007
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Pardon my noobish question, but I am curious to know What is Temperature units? If neither degrees C nor degrees F
|1st March 2008, 20:20||#32|
Join Date: May 2006
Thanked: 5 Times
|1st March 2008, 21:27||#33|
Distinguished - BHPian
Join Date: May 2005
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Engines are designed to operate at specific tolerances at certain specific temperatures. And the oil grades are determined to be used in a particular engine based on the tolerances of the internal components and also based on the optimum operating temperature that engine is designed to run at.
xW40 and xW50 have different viscosities or thickness when the engine is at the operating temperature. xW50 being more thick. Using a thicker oil in an engine designed to use xW40 range oil is not beneficial - unless the manufacturer recommends it under higher temperature operating conditions.
Being thicker the xW50 oil may not reach the places 'efficiently' in the engine which was designed to use a xW40 grade oil because the tolerances inside the engine might be too tight for a thicker oil even under optimum operating temperature of the engine.
When someone use a xW40 grade oil in an engine designed to take xW50 grade oil the tolerance between moving parts might be a bit too large for the less thicker xW40 oil to occupy and protect the moving parts. The big ends of almost all the engines are run on a oil film between the con rod and the bearing shells. The shear strength of the oil film and correct viscosity plays an important role in such situations.
Always use the correct grade of oil in the engines, when choosing the oil pay attention to the number that comes after 'W', at most of the places in India (except the colder regions up North) the number before 'W' can't be discounted. If a manufacturer recommends using a thicker grade for hotter climates use it.
And also the grading of xWx is not the same across all kinds of oil. For example gear oils if it says 90W then it's almost as thick as a 40W engine oil. This piece of information i found out yesterday as i was in a situation
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