The wheel loader had just come into the shop for PM and was scheduled for an oil change the next morning. We connected the Mobile Flushing Unit (MFU) to the rear differential and let it perform a hot flush overnight. The initial ISO could not be read accurately because the oil was too dirty. The starting ISO read 25/25/24 therefore the 4 micron count was over 400,000 particles. We started the filter about 4 pm and let it operate overnight. In the morning the ISO code was reduced to 15/13/11.