I acquired this meat grinder from a friend yesterday (7/4/17). No owner's manual. Through research I'm pretty certain it's about as old as I am (I'm around 50). It weighs 51 lbs. It's a beast. It's from General Slicing Manufacturing (no longer in business) Model D .73 hp 1700 rpm, approx Motors from most of those models were Westinghouse. I was told from my friend that the top port was for vegetable oil. Wouldn't it be better if food grade gear oil were put in there? I know veg oil can get rancid. I only plan on using it once or twice a month at this point. I'm just getting started making sausage. If it does take food grade gear oil, can you all make a recommendation as to what to use? If it doesn't take food grade gear oil, what can you recommend? If you need more info I will do my best to provide. Many thanks to a newbie in sausage making.