I've cut a lot of glass before, and you don't put oil or anything on the glass..
Just wipe your index finger across where you want to cut it, and then use a glass cutter, dipped in turpentine. The carbide cutter I used, could be filled with turpentine. And then you use a straight ruler-like piece of wood, that you fasten onto the glass with some rubber padded quick grips.. And then slide the cutter - not hard or too fast, but just so you can hear it makes a squeeky sound ! Just be careful when you break it off. :o)