Two methodologies for elemental analysis of lubrificant oil, fuel oil and biodiesel are proposed, employing inductively coupled plasma optical emission spectrometry and inductively coupled plasma mass spectrometry with dynamic reaction cell. The methodologies combine the facility and fastness of sample preparation through direct dilution in organic solvents, without any pretreatment, with the multielemental capability of these spectrometric techniques. In ICP OES, the analytical results for the micronebulizers PFA-100 and Miramist were evaluated using two certified reference materials, NIST 1634c (residual fuel oil) and NIST 1085b (wear metals in lubrificant oil). Ar and O2 flow rates were optimized employing a high resolution experimental design was realized, with replicate experiments and triplicate at the central point. Improvement in the signal-to-noise ratio were observed for Ag, Al, B, Ba, Ca, Cr, Cu, Fe, Mn, Si, Ti and V and the highest ratios were obtained with the PFA-100 micronebulizer. The Ar and O2 flow rates were optimized in order to improve these ratios. For Miramist, 0.50 L min(-1) (Ar) e 0.020 L min(-1) (O2) were used and, for PFA-100, 0.45 L min(-1) (Ar) e 0.025 L min(-1) (O2). The reference materials (NIST 1634c and NIST 1085b) were analyzed for validation of the method and the highest recoveries were obtained for the PFA-100 micronebulizer, with results between 93% and 110%. The limits of detection for both micronebulizers were very similar, between a range of 0.48 kg(-1) (Mn) and 15.8 ug kg-1 (Al). In DRC-ICP- MS, a central composite design was realized for the optimization of the plasma operational conditions. The nebulizer and auxiliary flow rates showed a relevant influence on Ba++ and LaO+ content and In intensity. A compromising condition was employed, being 0.42 L min(-1)(Ar nebulizer flow rate), 0.1 L min(-1) (O2 flow rate) and 1.2 L min(-1) (auxiliary flow rate). In order to minimize spectral interference, methane was adopted in this work as reaction gas. The operational conditions of the reaction gas flow rate and rejection parameter q (Rpq), were optimized to minimize the interferences on isotopes, such as 52Cr and 56Fe. Two reference materials (NIST 1634c and NIST 1085b) were employed for method validation and the recoveries were between 90% and 110% for most elements, being the limits of detection between 0.02 ng g(-1) (52Cr) and 7.4 ng g(-1) (40Ca). The results obtained for the reference material NIST 1085b by the two proposed methods were in agreement at a 95% confidence level and did not show difference higher than 10% for most elements. The results obtained by elemental analysis of lubricant oils using the ICP OES methodology showed that it is possible to evaluate equipment wear through the analysis of its oil by the proposed methodology, since a significant increase of some elements concentrations, such as Fe, was detected in used lubricant oil samples. The analysis of biodiesel samples by ICP-MS indicated the presence of elements that are not controlled by the Brazilian legislation.