When the crude oil temperature goes below the pour point value wax crystals will come out of solution and tend to plug lines and filters. Additionally, the wax deposited in tanks decreases the storage capacity. In general, wax deposition can cause problems in production, storage, transportation, and consumption. Pretreatment of the crude oil with flow improver or pour point depressants has received the greatest acceptance due to its simplicity and economy. Four commercial additives were evaluated as pour point depressant for fuel oils. The structures of the commercial additives were confirmed by FTIR spectra. The results indicate that the n-alkanes carbon distributions display an obvious normal distribution in fuel oils. The distributions of high carbon n-alkanes are all broad so that wax crystals not precipitate in fuel oil at low temperatures is good. These commercial additives were tested as pour point depressants for fuel oil. The obtained data revealed that the prepared compounds depress the pour point of the fuel oil successfully. Comparison of structures of wax crystals in untreated and treated fuel oil was also done by photomicrographic analysis.