Marsap services offers heavy-fuel oil stability. Refineries process different crudes, it becomes important to ensure that there is a compatibility of blends of hfo processed from various crudes. Also, additive usage can be optimized andcomparison made between manufacturers of different brands of additives to assess, which are more efficient. Marsap offers the turbiscan thfo analyzer, which is based on the principle of multiple light scattering and measures the stability reserve of the hfo wrt ageing simulation precipitation of asphaltenes in alkane. The method is objective and repeatable and comes up with a single result separability number per astm d 7061.