beden1

Just use a razor blade to scrape the crap off. Then, and if you want to, use Rain-X to make it easier to remove the next time.

nwGTS

I would not advise using a razor blade in any regard. But if you do, make sure the glass is well lubricated or you are guaranteed to scratch the glass.

Tar and road oil is petroleum based.
Bug guts are organic lipids.
Both will be removed with a detergent or solvent.
It's glass, so don't use a solvent. Use of a detergent is fine but should be mild.
So, soap and water will do it for the bug guts but the tar and road oil will need something a bit more concentrated but still mild. That leaves us with readily available goo-gone or goo gone like products. You'll need to use a less concentrated soap and water solution to remove the goo gone but then your windshield will be clean. As others suggested including beden1, products like Rain-x or similar window sealants will prevent oil, tar and bug deposits in the future (though not all of them).

beden1

It's glass. Razor blades work well on glass. The steel does not scratch glass. But, you could use a spray detailer as a lubricant if you are reluctant.

nwGTS

While according to the Mohs scale steel is softer than glass, that is stainless steel and pure Silica glass or quartz. Glass in cars and most home windows is not complete silica but is also baked with sodium oxide, lime and other compounds. Those silica compounds are softer than stainless steel and can scratch if not scraped properly. However, most new construction and auto glass is tempered and well made tempered glass will not scratch easily (though it can). Hedge your bet and use a diluted detergent in most cases or you could use a spray detailer as beden1 mentioned, but a diluted detergent usually is best as it is easier to clean up afterward. If anything, make sure the razor you use is brand new and does not have rust or debris on it as it's the contaminants that scratch the glass most often and not the steel itself.

LexVan

FYI. Don't razor scrape your side windows. Those are factory coated for rain repulsion.

Marine Blue

Clay on windsheilds has been used for years by detailers and it works well to get the very small amounts of tar and other debris that a normal window cleaner can't remove.

To clean glass I use a blend of isopropyl and water in a 65/35 blend (assuming 70% isopropyl). This is used in combination with a microfiber glass towel. No lint, no hazing and enough bight to remove bugs easily.

AndrewP

Have been using Aquapel by PPG for years. It lasts six months in NE on the windshield and longer on the exterior mirrors and side/rear windows.

Took advice on denatured alcohol/water for windows. Works great. Now have to get out the GooGone for the rubber from yesterday's track work.

myw

they have the lubricated bug sponge that should be available at any auto parts store. the meguires one works excellent.

doesn't scratch paint… and I've used it on headlights as well and it works WONDERS on tar. i had this massive gunk of tar all over my car and the bug sponges are a lifesaver. it works FAST as well.

Domer911

this

Domer911

this

dalancroft

That's what I was going to say as it's what I use.

NAM VET

I gave up on RainEx years ago. I found while it beaded water nicely, if i used my wipers, they started skipping and chattering. I use an occasional clay bar and the Stoner product with surgical cloths i wash separately from any wax or polish cloths. It all works for me.

all the best...

mikes70

DO NOT use used razor blades on glass, it will scratch. NEW Razor blades are fine on glass, but only new ones. IF you do use them, do not go back and forth, treat it like your shaving your face, with lubricant and in one direction.

I've been in the glass biz for 29 years and know a thing or two bout glass.

I use 0000 steel wool and glass cleaner when the going gets rough. But it still wont cut tar....

Adam Ginsburg

Microfiber cloth with the goo be gone? Do you wash the windshield after goo be gone?

Newt Gomez

For bugs and water spots on glass, 0000 fine steel wool with window cleaner as a lubricant works wonders. It doesn't scratch glass due to glass being really hard. I have had excellent luck on paint with bug and tar remover from products on autogeek.net. A clay bar with your standard soap and water wash may help as well, but the main goal is always to use the least contact with the paint as possible. On top of your typical sealant/wax/coating regimen, a silicone spray on coating every couple months really helps out with paint maintenance.
AMMO NYC is a great youtube channel that goes in to great detail about this kind of stuff.