To measure viscosity at different temperatures, the viscometer is placed in a water bath. The higher the viscosity, the longer it will take the fluid to drain through the tube. The suction is removed, and the time it takes for the fluid to drain out is measured. Fluid is drawn up from the cup on the lower left into the tube on the right, using a suction bulb. Viscosity of liquids can be measured with a special piece of glassware called a viscometer (see Figure 1). For an engine lubricant, it is important that the viscosity does not change significantly as the temperature increases. Cooking oil has a higher viscosity-it pours more slowly than water. Water is an example of a fluid with low viscosity-it pours easily and quickly. The viscosity of a fluid is a measure of the fluid's resistance to flow.

One way of measuring an oil's ability to lubricate is to measure its viscosity. The oil must be able to keep the piston moving smoothly at cold temperatures (when the engine first starts up) and also at the normally high operating temperature of the cylinders. Lubricate over a wide temperature range.' (Thibault, 2001).Seal piston and liner for optimum engine efficiency.Lubricate engine moving parts to reduce friction and prevent wear.Without oil, the piston would not be able to move in the cylinder-the engine would seize up and be ruined.

The oil is a lubricant-a slippery liquid that allows the piston to slide freely within the cylinder. In order to keep the pistons moving smoothly in the cylinders, there is a thin film of motor oil between the piston rings and the cylinder wall. The internal combustion engine that powers your family's car has moving parts that work at high temperatures for billions of cycles over its lifetime.

Viscosity test science fair experiments