[sanddrag]

For aluminum, there's this stuff called A9 (I think that's what it is) that is green in color and it comes it a little rectangular can. Tap Magic is good but the smell gets to me after a little while and I don't like it on my hands.

My personal favorite for aluminum and/or steel is what is commonly used in CNC machines. It is some sort of water soluble oil. I believe you are supposed to mix something like 2 parts water to one part oil. The oil is motor oil colored but when mixed with water it is sort of a cream colored. I've seen it come in a blue jug, although I don't remember the name of it.

One other thing I used once for cutting aluminum with a good amount of success was RIDGID brand oil (that I think was made for pipe threading). It was like night and day, almost like dull blade vs sharp blade. Home Depot would be the only place that has it if they still make it; it was quite a while ago.

In a pinch, almost any oil is better than no oil. I've used motor oil quite a few times for steel. Smells really bad, but works better than nothing. Even liquid wrench works to some extent, although you'll want to watch out for fumes.