How do you get rid of windshield streaks?

Use two cloths: one damp for cleaning, one dry for buffing. Work in straight lines, not circles.

Can you use Windex on a windshield?

On the exterior, yes. Avoid on interior near aftermarket tint, as ammonia damages tint film.

Exterior: every car wash. Interior: every 2-4 weeks.

White vinegar sprayed on and left for 5 minutes, then wiped. A clay bar treatment works for severe spots.

Automotive

Keeping your windshield clean protects your investment and improves both appearance and performance. Here's the right way.

1
Clean the exterior
Spray Streak-Free Glass Cleaner on the windshield. Wipe in straight horizontal strokes with a microfiber cloth, then buff dry.
2
Clean the interior
Spray cleaner on a cloth (not the glass). Wipe in vertical strokes for the interior side.
3
Remove film buildup
For the hazy interior film from dashboard off-gassing, use rubbing alcohol on a microfiber cloth.
4
Detail the edges
Wrap a cloth around a flat tool to clean where the glass meets the dashboard and rubber molding.

TIPUse horizontal strokes outside and vertical inside. This tells you which side has streaks.
TIPThe interior film is caused by vinyl dashboard off-gassing. It builds up slowly and causes dangerous glare.
TIPClean windshield wipers with rubbing alcohol monthly to prevent streaking during rain.

XUsing ammonia-based cleaners near tinted windows, which degrades the tint film.
XCleaning in direct sunlight, which dries cleaner before you can wipe, causing streaks.
XUsing paper towels, which leave lint and don't clean as effectively as microfiber.

Plasticizer off-gassing from dashboard vinyl creates a film. Clean with rubbing alcohol or vinegar solution.