The contamination of gray forest soils with oil and diesel fuel at concentrations of 50, 150 and 300 ml/kg is shown to lead to a decrease in their capillary moisture capacity. When applying 50, 150 and 300 ml/kg of oil, this indicator decreased from 62 (corresponds to the best capillary moisture capacity) down to 22.6, 19.1 and 12.6%, respectively. The effect of diesel fuel on the capillary moisture capacity of the soil was similar. In the presence of 50, 150 and 300 ml/kg of this oil product, the capillary moisture capacity of the soil decreased from 62% down to 28.3, 20.0 and 13.8%, respectively. As a result of the introduction of the microbial oil-destroying preparation “DOP-UNI” and subsequent exposure for 3 weeks, it was possible to partially restore this agrophysical characteristic of the soil. Even during such a short exposure time, the capillary moisture capacity of the oil-contaminated soil (50–300 ml/kg), after treatment with the biological preparation, increased by 1.3–1.8 times compared to an untreated oil-contaminated sample. However, its values still remained lower than in uncontaminated soil samples. A similar trend was noted in our experiment with diesel fuel. In addition, the treatment of oil-contaminated soil with the biological preparation “DOP-UNI” for 3 weeks led to a decrease (by ~20%) in phytotoxicity at the level of oil contamination up to 150 g/kg. The obtained data allow us to judge the prospects of using the biopreparation “DOP-UNI” for soil remediation in the case of contamination with petroleum products and restoration of their agrophysical properties. At the same time, lowering the temperature down to 10°C did not significantly affect the effectiveness of the biopreparation, at least in the described 3-week experiments. This indicates the possibility of its use in low-temperature conditions, which is typical for the main oil production sites in the Russian Federation.