This test method gives primary biodegradation of the lubricant, test substance. The biodegradation is induced by the external inoculums. The reference sample and test samples are incubated at specific temperature until sufficient colonies were visible to enable counting. The residual content of test substance is determined using infrared spectrophotometry. The test is carried out using Sarbi make ‘biodegratation apparatus.’ The apparatus mainly consist of Incubators with glassware and accessories.