I have a Bondioli & Pavesi (made in Italy) gear box on my Rears Flail mower and it has Schaeffer High Temp #209 Moly SAE90 in it. I would like to change the gear lube but the smallest container I can find of the #209 is a five gallon bucket for $122 which would be enough to outlive the flail as I dont need it for anything else. Can I use 'Schaeffer #293 Synthetic Plus 75w-90' instead as I found that in a one quart container? Should I flush out the gear box prior to adding the new lube and if so what is the best thing to use?