engleski

Influence of engine oils dilution by fuels on their viscosity, flash point and fire point

In this project the influence of dilution of synthetic and mineral engine oils with two commercial fuels – gasoline (type Eurosuper 95) and diesel fuel (type eurodiesel) was studied. The situation that could really occur in the automotive engine was simulated – a breakthrough of unburned fuel to engine oil and its mixing and dissolution. Viscosity, fire point and flash point were chosen as the most important parameters to follow the changes in oil-fuel mixtures. The dilution range was between 0 and 10 wt% of fuel in the oil-fuel mixture. The samples used in this investigation were bought directly from the two producers present on the Croatian market, without further modification. The samples were multigrade mineral and synthetic oils – mineral oil with SAE gradation 15W-40 and synthetic oil with SAE gradation 5W-30.The changes of oil properties were too high for assumed safe use in engines in the case of oil dilution with 10 wt% of gasoline. The dilution of oil with 5 wt% of gasoline was maximal level of dilution that could be expected to be still adequate for use in engines, because the flash points of these mixtures were mostly near 150 °C, which is assumed as maximal allowed working temperature of engine oil. The properties of mixtures of the same oils with diesel fuel showed smaller changes than mixtures with gasoline.

engine oil; fuel; viscosity; flash point; fire point

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