I changed mine without much ado. Yes you fill, run and add to get fluid visible in the reservoir. Then run for a couple of minutes and start working the levers back and forth till you purge the air out of the system....just takes a few minutes. Then check for maybe half an inch of visible fluid when the unit hasn't been run for awhile...overnight. I found syn. 20w-50 at wallyworld, may have been their house brand but I have no problems with their house brand oils...they work in my equipment. I do use Rot. T6 full syn in my red tractors.