Inside of windshield w/ bad streaks....

I have windexed the damn thing a hundred times, it looks better but still very noticable. Still has streaks from when I had bought it and they must have washed it with something greasy...
Any tips on how to get this stuff off?

Always clean glass out of direct sunlight & while cool.

1. Use a good quality glass cleaner, like Stoner
2. Spray chemical on window, scrub with soft sponge or fine steel wool.
3. Dry with microfiber towel
4. Repeat if needed

If heavy cleaning is needed, 1 time usually isn't enough. Also cover your dash with another towel so you dont drag anything on the glass. Only use CLEAN towels.
http://topoftheline.com/glassstreaking.html