I did the same thing with the NP205 in the rig right now. When I went to change the gear oil before taking her out for the first trip around the block, I was shocked to find what looked like mud in there. (I swear my brother couldn't take care of a moped, let alone a truck) But did the diesel trick, put new gear oil in it, and then drove it around the block again and checked the gear oil. Clean as a whistle. (Now I just gotta hope the bad oil didn't do to much damage in there)woody said:When my SM465 needed a cleanout, I used diesel fuel. Took it for a couple spins around the block, and drained 'er out.