Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

I bought an old John Deere 522 (Simplicity 555), bought an operators manual off of Ebay and read up on the machine. This machine needs a little help, I have to replace the impeller pulley. I read in the book about the fluids for the Peerless 3 speed trans and the impeller gearbox. It said to check the fluids, remove the pipe plugs and so on. They were both low so I topped them off with 80W gear oil which is what the book called for. Shortly after, there was gear oil everywhere. I took the trans apart and apparently Bentonite was added at one point. Right now, I'm draining the gear oil from the trans, my question is, will mixing the two possibly ruin the gears and should I clean out the trans and start fresh? thx, chuck