I just got a Express SR NX50 for free from a friend and have a question. I know it has separate oil and gas tanks but what goes in the filler on the right side of the engine? It has what looks like an oil fill cap but I am finding conflicts as to what should be put in it. I have found one place where they say 90 weight gear oil and the local Honda shop says just 10/40 (and he didn't seem like he was so sure). Thanks in advance for the help.