A tractor hydraulic fluid composition comprising: (a) a major amount of an oil of lubricating viscosity, and (b) a detergent system comprising: (i) a low overbased alkaryl sulfonate detergent having a total base number of 2 to less than 150, the total base number determined in accordance with ASTM D2896; (ii) a high overbased sulfonate detergent having a total base number of 300-800 mg KOH/g on an actives basis, the total base number determined in accordance with ASTM D2896; and (iii) a high overbased phenate detergent having an alkyl group derived from an isomerized normal alpha olefin having from about 10 to about 40 carbon atoms per molecule, the high overbased phenate detergent having a total base number of 300-600 mg KOH/g on an oil free basis, the total base number determined in accordance with ASTM D2896, and wherein the high overbased phenate detergent has an isomerization level of the normal alpha olefin of from 0.10 to 0.40, wherein I is determined by hydrogen-1 NMR using the equation I = m / m + n where m is NMR integral for methyl groups with chemical shifts between 0.3 ± 0.03 to 1.01 ± 0.03 ppm, and n is NMR integral for methylene groups with chemical shifts between 1.01 ± 0.03 to 1.38 ± 0.10 ppm, wherein the high overbased phenate detergent is a calcium phenate detergent, and wherein the composition comprises from 0.005 to 0.08 wt.% Ca from the high overbased phenate detergent. (a) a major amount of an oil of lubricating viscosity, and (b) a detergent system comprising: (i) a low overbased alkaryl sulfonate detergent having a total base number of 2 to less than 150, the total base number determined in accordance with ASTM D2896; (ii) a high overbased sulfonate detergent having a total base number of 300-800 mg KOH/g on an actives basis, the total base number determined in accordance with ASTM D2896; and (iii) a high overbased phenate detergent having an alkyl group derived from an isomerized normal alpha olefin having from about 10 to about 40 carbon atoms per molecule, the high overbased phenate detergent having a total base number of 300-600 mg KOH/g on an oil free basis, the total base number determined in accordance with ASTM D2896, and wherein the high overbased phenate detergent has an isomerization level of the normal alpha olefin of from 0.10 to 0.40, wherein I is determined by hydrogen-1 NMR using the equation I = m / m + n where m is NMR integral for methyl groups with chemical shifts between 0.3 ± 0.03 to 1.01 ± 0.03 ppm, and n is NMR integral for methylene groups with chemical shifts between 1.01 ± 0.03 to 1.38 ± 0.10 ppm, (i) a low overbased alkaryl sulfonate detergent having a total base number of 2 to less than 150, the total base number determined in accordance with ASTM D2896; (ii) a high overbased sulfonate detergent having a total base number of 300-800 mg KOH/g on an actives basis, the total base number determined in accordance with ASTM D2896; and (iii) a high overbased phenate detergent having an alkyl group derived from an isomerized normal alpha olefin having from about 10 to about 40 carbon atoms per molecule, the high overbased phenate detergent having a total base number of 300-600 mg KOH/g on an oil free basis, the total base number determined in accordance with ASTM D2896, and wherein the high overbased phenate detergent has an isomerization level of the normal alpha olefin of from 0.10 to 0.40, wherein I is determined by hydrogen-1 NMR using the equation I = m / m + n where m is NMR integral for methyl groups with chemical shifts between 0.3 ± 0.03 to 1.01 ± 0.03 ppm, and n is NMR integral for methylene groups with chemical shifts between 1.01 ± 0.03 to 1.38 ± 0.10 ppm,