When compared to the kinematic viscosity standard for diesel and biodiesel (in the ranges of 2–4 mm2 s1 and 3.5–5 mm2 s1, respectively), the contour plot (Fig. 4a) shows that a large area for several proportions can be selected when maintaining the viscosity of the biodiesohol within the biodiesel standard. Furthermore, an increased kinematic viscosity standard for biodiesel in agriculture machinery in Thailand (up to 8 mm2 s1) implies that the proportion of the CJO in a blend of Jatropha biodiesohol can be up to 50%; this proportion is still able to form a single-phase and clear microemulsion (as shown in Fig. 1). However, other properties should still be investigated for full compatibility.