newbie, Bachmann 0-6-0 does not smoke

[FatherOf4]

I bought a used Bachmann Pennsylvania 0-6-0 for my kids, but first try it doesn't smoke. I can smell the oil heating, but noticed some oil on the undercarriage of the engine. Otherwise the engine runs well. I'm thinking the oil tank is cracked, but am leary of opening it to check. Can I safely open it without parts coming loose inside, and is there a way to repair the tank, if that's the problem?

[stationmaster]

Reservoir is too full. Yes he engine should be ableto be disassembled without parts flying all over.

[FatherOf4]

Thanks, stationmaster, for the quick reply!!
Kids were too excited to wait for me to find a manual, so I put three drops in the tank. As for taking it apart, I usually have bad luck with small toys so I didn't want to disassemble without some prior indication of what I would be getting into. I'll try again tonight and see how it does with one drop.