The effect of ionic liquids in terms of minimum film thickness is shown in รูปที่ 5(b). As a general trend the lubricants with higher viscosity results into thicker lubricating films. Keeping the operat- ing, geometric and material parameters constant, the lubricants with higher viscosity results into thicker lubricating films. The same trend has been observed in the present study, the [C8C1 im] PF6 having highest viscosity reported thicker lubricating film and the [C4C1 im]TF2N having lowest viscosity reported thinnest lubricating film.