## 4 Conclusions  
The aim of this study was to see how the additives of effective microorganisms and silver would affect selected engine performance parameters including fuel consumption and exhaust gas composition. The tests were carried out for diesel fuel with 2% and 5% additives, for idling and two engine power loads--20 kW and 30 kW. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline  & & \multicolumn{3}{c}{**NO, [ppm]**} & \multicolumn{5}{c}{**CO [ppm]**} \\ \hline
**Engine Load** & **Pure Oil** & **Additives** & **Concentration 2\%** & **Concentration 5\%** & **Pure Oil** & **Additives** & **Concentration 2\%** & **Concentration 5\%** \\ \hline \multirow{4}{*}{0 kW} & \multirow{4}{*}{289} & SS & 271 & \(\downarrow\)6.2\% & 251 & 13.2\% & SS & 364 & \(\downarrow\)16.2\% & 425 & \(\downarrow\)2.1\% \\  & & CS & 266 & \(\downarrow\)8\% & 247 & \(\downarrow\)14.6\% & CS & 398 & \(\downarrow\)8.3\% & 415 & \(\downarrow\)4.4\% \\  & & EM\_fl & 266 & \(\downarrow\)8\% & 278 & \(\downarrow\)3.9\% & EM\_fl & 397 & \(\downarrow\)8.5\% & 398 & \(\downarrow\)8.3\% \\  & & EM\_cer & 259 & \(\downarrow\)10.4\% & 259 & \(\downarrow\)10.4\% & EM\_cer & 389 & \(\downarrow\)10.4\% & 420 & \(\downarrow\)3.3\% \\ \hline \multirow{4}{*}{20 kW} & \multirow{4}{*}{874} & SS & 846 & \(\downarrow\)3.2\% & 830 & \(\downarrow\)5.1\% & SS & 667 & \(\downarrow\)28.7\% & 957 & \(\uparrow\)2.4\% \\  & & CS & 851 & \(\downarrow\)2.6\% & 852 & \(\downarrow\)2.5\% & CS & 844 & \(\downarrow\)9.8\% & 971 & \(\uparrow\)3.9\% \\  & & EM\_fl & 860 & \(\downarrow\)1.6\% & 822 & \(\downarrow\)6\% & EM\_fl & 876 & \(\downarrow\)6.3\% & 910 & \(\downarrow\)2.7\% \\  & & EM\_cer & 865 & \(\downarrow\)1.0\% & 825 & \(\downarrow\)5.6\% & EM\_cer & 905 & \(\downarrow\)3.2\% & 926 & \(\downarrow\)1.0\% \\ \hline \multirow{4}{*}{30 kW} & \multirow{4}{*}{1222} & SS & 1174 & \(\downarrow\)4\% & 1189 & \(\downarrow\)2.7\% & SS & 1206 & \(\downarrow\)25.3\% & 1575 & \(\downarrow\)2.5\% \\  & & CS & 1200 & \(\downarrow\)1.8\% & 1240 & \(\uparrow\)1.5\% & CS & 1518 & \(\downarrow\)6.0\% & 1601 & \(\downarrow\)0.9\% \\  & & EM\_fl & 1220 & \(\downarrow\)1.7\% & 1095 & \(\downarrow\)10.4\% & EM\_fl & 1616 & \(\uparrow\)0.6\% & 1639 & \(\uparrow\)1.5\% \\  & & EM\_cer & 1190 & \(\downarrow\)2.62\% & 1105 & \(\downarrow\)9.6\% & EM\_cer & 1658 & \(\uparrow\)2.7\% & 1701 & \(\uparrow\)5.3\% \\ \hline \multicolumn{10}{c}{**CO: [\%]**} & \multicolumn{5}{c}{**CO: [**5**]**} & \multicolumn{5}{c}{**Fuel Consumption [dm\({}^{3}\)/h]**} \\ \hline
**Engine Load** & **Pure Oil** & **Additives** & **Concentration 2\%** & **Concentration 5\%** & **Pure Oil** & **Additives** & **Concentration 2\%** & **Concentration 5\%** \\ \hline \multirow{4}{*}{0 kW} & \multirow{4}{*}{2} & SS & 1.8 & \(\downarrow\)10.4\% & 1.7 & \(\downarrow\)15\% & SS & 4.5 & \(\downarrow\)4.5\% & 4.6 & \(\downarrow\)2.5\% \\  & & CS & 1.9 & \(\downarrow\)5.0\% & 2 & \(\%\)5 & CS & 4.6 & \(\downarrow\)2.5\% & 4.8 & \(\uparrow\)4.6\% \\  & & EM\_fl & 2 & \(\%\)0 & 1.9 & \(\downarrow\)5.0\% & EM\_fl & 4.6 & \(\downarrow\)2.5\% & 4.8 & \(\uparrow\)4.6\% \\  & & EM\_cer & 2.1 & \(\uparrow\)5.0\% & 1.8 & \(\downarrow\)10\% & EM\_cer & 4.6 & \(\downarrow\)2.5\%The additives were found to have no significant effect (neither positive nor negative) on selected engine operating parameters including the engine speed; the cooling water and lubricating oil temperature; the exhaust gas temperature; and the air intake pressure. They did, however, affect the hourly fuel consumption and exhaust gas composition. The best fuel consumption results were achieved with a 2% silver solution. This addition caused fuel consumption to drop by up to 3%. Higher concentrations in most cases increased this consumption by up to 6% for liquid effective microorganisms.As part of the exhaust gas composition studied, the effects of the additives on the three most important components of the exhaust gas from an environmental point of view were analysed.