My old Toro rider has a Hydro-gear transmission. It is a sealed unit, filled for life, a notion that I strongly oppose.
I intalled a used one at 540 hours because the original failed catastrophically. I think it failed because the oil was never changed (it was very black).
Now at 1070 hours I removed the hydrostatic unit and drained the oil thru the vent by turning it upside down. Again, the new oil I had installed 530 hours ago was black. Perhaps 200 hours would be a more appropriate OCI.
Would it be permissible to add ARX to the new oil? The lubricant capacity is about 2.25 quarts and calls for 20W50 engine oil (I use Mobil 1).
