The assay was conducted in Pelotas, Rio Grande do Sul-Brasil, to compare the effect of used engine oil with to paraquat (Gramoxone) applied during the physiological maturition of soybean seeds (Glicyne max (L.) Merrill), Bragg variety. The oil doses were 5.3, 8.5 and 12 l/ha. The desiccation intensity was determined and 30 pods per plot were periodically collected to follow the humidity content of the seeds, to 18%. The humidity was later reduced to 10.5 +0.5 and 2.0 kg of seeds were stored, in cotton bags,during 6 months under the environmental conditions at the Centro de Entrenamiento de Semillas of the Federal University of Pelotas. The seeds were subjected to germination, vigor and phytosanitary tests at harvest time and after 3 and 6 months of storage. Under the conditions of this trial, the doses of 12 l/ha of oil and 2 l/ha of paraquat: a) act as desiccants for soybean plants, b) favors the production of seeds with better viability and vigor after 6 months of storage and c) guarantied better sanitary seed quality after 6 months of storage.