In this paper, we present, design and analyze a metamaterial (MTM) based sensor to distinguish different types of gasoline and diesel samples. Electromagnetic characterization of the samples is completed experimentally and the obtained data is used in the numerical analysis and in the design of the proposed sensor. Unlike the other studies performed in the literature, this structure offers a highly efficient sensing ability and operates in x-band frequency regime. The designed structure is fabricated and the experimental studies are carried out in the related frequency range. It is also demonstrated that numerical results are in a good agreement with the measurement results. The proposed sensor has highly enough bandwidth to sense the fuel oil samples including gasoline and diesel with different characteristics. The suggested structure can be used effectively as a fuel oil sensor in automotive industry. Besides, due to its simple design and high efficiency, the proposed structure can be adjusted to any other liquid sensing application in any desired frequency band by simple adjustments on the dimensions of the structure.