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DARK COLORED OILS: Dark
colored oils in the test tube may make it difficult to see the
sphere. To overcome this, follow standard test procedure under
READING. Then, with your back to the light (Fig. 6) and full light
on the scale, (Fig. 7 & 8) tilt reference tube toward you 90 degrees
to bring the sphere in the test tube into sight. The point on the
scale corresponding to the position of the sphere indicates the
viscosity of the test oil direct at which it was rated in
Centistokes at 40° C. (Fig. 8)
The VISGAGE is designed and constructed to test the viscosity of
new and used oils but not sludge.
Whenever the sphere in the test tube can no longer be seen, you will
know the oil is so badly fouled with contaminants that it needs to
be changed immediately or cleaned by any of the appropriate cleaning
methods.
VISCOSITY INDEX (VI):
The reference tube contains certified oil with a viscosity index of
95 VI. Best accuracy is achieved when the oil being tested has a VI
near the VI of the reference oil, and several identical readings on
the scale indicate temperatures of both tubes are equal. If the VI's
of the oils are far apart (for example, 95 VI in reference tube, 40
VI in test oil), warm VISGAGE to 40° C, and then take readings.
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