I was checking the gear box oils on my Lexion 590r today. The grain tank auger gear box says in the book is maintenance free. I think it is maintenance free because it is so hard to get to. I took the plug of the top of the gear box and there was very little to no lubrication in it. I poured some 80-90 gear oil in it. Does anyone know what the proper oil or grease to put in this gear box? Has anyone had on of these gear boxes go bad? With little lubrication In it I was wondering how long it would last.