Whether its A Semi or Tractor,  hydraulic fluid and grease buildup is a common problem.  For most Semis and tractors the most common build-up spots are typically found near brake pads and at hydraulics hook-up lines. The first step of our wash is hot steamed pressurized water to get dirt, pollen, bugs, or mud off. We then use a degreaser to cut through all the grime therefore when we follow up with our last step (which is a wash/wax application) cutting through dirt and grime before applying wash and wax is very crucial because it allows the wax to penetrate and work the paint instead of working on dirt. Which helps the paint last longer, prevents discoloration, prevents fading, and provides the shine that we all long for!