High viscosity is the major problem preventing the use of vegetable oils and animal fats directly in
diesel engines. The viscosity of the waste cooking oil was determined by using a falling ball
viscometer. Triplicate samples were used for the experiments. It was observed that the average
viscosity of canola oil sample was measured to be 70 mm2
/sec at 21°C. The viscosity of biodiesel ethyl
ester measured at 40o
C was found to be 5.03 mm2
/sec which was in the range recommended by
ASTM. The ASTM standard for biodiesel viscosity is 1.9-6.0 mm2
/sec at 40o
C.
The density of waste cooking oil measured at 21o
C was 90 g/cm3
. The density of biodiesel at 15o
C
was found to be 87 g/cm3
. Tate et al. [23] reported that density is a function of temperature and
decreased linearly for canola methyl esters, soy methyl esters, and fish oil ethyl esters by 1.23 kg/m3
o
C for temperatures between 20–300o
C.