Im trying to clean a windshield of a vehicle that’s been sitting outside for years, and it has a foggy area it looks like a stain with drip marks. It’s on the outside, I’ve tried razor blades, mineral spirits, vinegar, even polishing compound. It’s a little better, but still large and too bad to use in current condition. When water or glass cleaner is on it it’s gone, but when dry it’s back. Any ideas?