Acta Univ. Agric. Silvic. Mendelianae Brun. 2014, 62, 1015-1020
Published online 2014-12-02

Excessive Additive Effect On Engine Oil Viscosity

Vojtěch Kumbár, Jiří Votava

Department of Technology and Automobile Transport, Faculty of Agronomy, Mendel University in Brno, Zemědělská 1, 613 00 Brno, Czech Republic

The main goal of this paper is excessive additive (for oil filling) effect on engine oil dynamic viscosity. Research is focused to commercially distribute automotive engine oil with viscosity class 15W–40 designed for vans. There were prepared blends of new and used engine oil without and with oil additive in specific ratio according manufacturer’s recommendations. Dynamic viscosity of blends with additive was compared with pure new and pure used engine oil. The temperature dependence dynamic viscosity of samples was evaluated by using rotary viscometer with standard spindle. Concern was that the oil additive can moves engine oil of several viscosity grades up. It is able to lead to failure in the engine. Mathematical models were used for fitting experimental values of dynamic viscosity. Exponential fit function was selected, which was very accurate because the coefficient of determination R2 achieved high values (0.98–0.99). These models are able to predict viscosity behaviour blends of engine oil and additive.


The research has been supported by the project TP 4/2014 “Analysis of degradation processes of modern materials used in agricultural technology“, financed by IGA AF MENDELU.


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