As alot of the other guys have already said there are a ton of differnt things out there that work. Personally I like olive oil, but my favorite by far is bear oil, I usually cold press the fat first for some really fine oil that I use for lock internals and then render the oil out of the fat for general use as lube and rust prventitive. Never really had a problem with rust and the bear oil stays prett fluid even as cold as it gets anywhere here in MI. Coon oil and beaver oil works pretty well to. The only drawback with the whole bear grease is that you have to get ahold of the bear first (usually not a problem, but I have the worst luck on drawing a bear tag, I have only drawn twice since they went back to the lottery hunt here).