You can use any type of oil for drilling metal. I usually use transmission fluid. Heavier oils work well, too. Transmission fluid starts to smoke when it gets too hot, which is a good clue to slow down.
The softer the material is, the faster your drill should spin and the less pressure you should apply. If you push too hard and spin your drill too slowly, the hole will wander. This rule applies to soft metals and woods. Use plenty of lube on thick aluminum or the metal will gall and stick to the drill and cause it to drag and possibly break off, or at least it will cause your hole to get all bungled up. Also, you'll want to back the drill out and clear the chips frequently in thick aluminum for the same reason.
The harder the material is, the slower your RPM and the more pressure and more oil you should use. High RPM on hard materials will burn the bit. High pressure is completely safe if you are using enough oil.
Where I used to work years ago we used pneumatic drills, plenty of cutting oil, and I don't know what kind of bits. We used the same bits for aluminum, steel, titanium, whatever, and if you did it right they were good for everything. For titanium, we used super low RPM, so slow you could see the bit going around. If you used lots of oil and pushed hard enough to give you a cramp in your arm, you could watch ribbons of titanium come off the rivet.
I don't think you need the absolute best drill bits in the world to make it work. You can get by with "good" bits. Just don't buy the worst ones. A go kart enthusiast is usually working with nothing harder than mild steel anyway. Of course, if you do get the best drill bits, take care of them by lubing and not overspeeding in hard metal and they'll be a pleasure to use.
