My rear window glass has very old, very baked on tint film on both sides, as well as lots of sticky gunk from the tint and stickers. What's the best way to clean all this off? The tint is so attached, it almost feels like part of the glass! It must have been on there for quite some time, baking in the sun over decades. I've tried peeling it but, as you can see below, some ripped off, leaving the stubborn parts behind.

Thanks, Luke.

Oh man, rear window tint in a 914 is never good. Ruins vision out the back worse that other cars.

Just a google thing, maybe some ideas found in the link? ...

https://www.google.com/search?sxsrf=ALeKk03...DCA0&uact=5

glass cleaner as a lube (windex) and razor blade in a holder.

I like the small one. Hardware store should have one.

Mini-Razor Blade Scraper

I used a clothing steamer, and a single-edged razor blade in a holder; removed the tint from all the windows on an F-350 crew cab in just a few hours.

Amonia takes it off. I soaked rags in it and wrapped the whole window in saran wrap and let it sit for a day.
It can be easily be pealed off and the glue is disolved.

PineSol....get a couple of 2 gallon jugs (regular not lemon) at Home Depot and a homer bucket or a large tub. Soak it 1/2 at a time cover the bucket and glass sticking out with a garbage bag. Let it sit for a week or so then flip. Uses sponge with a greenie and ‘gently’ scrub with water, German glass is soft an a greenie with to much pressure will scuff it.

PineSol has a high ammonia content, is cheap and fairly benign stuff. Will make your garage smell piney fresh....LOL

I’ve used the PineSol soak for a lot of stuff over the years, cuts rust, grease, glues, gums, boogers, paint yet doesn’t seem to effect rubber...will make your aluminum case halves and cylinder heads shine. The worst it will do is remove zinc plating, if it’s silver or yellow zinc, it’ll be grey steel in a week.

For your back window, those long low tubs they put Christmas wrap in???

Click to view attachment

https://www.homedepot.com/p/ZEP-32-oz-Strea...12032/100676308

After trying Oven-off, Zep Orange Concentrate, Windex, solvents, alchohol, acetone, this is the stuff that flat out clean works.
Use a thin, flexible old school razor, always pushing away from appendages, use care to not snap the razor and slice off a fingertip.
Patience, sweat, determination, perseverance.
Never scrape across deposited heater elements, parallel.
Patience..

I don't know how effective or practical it would be for glass off the car, but there's a "trash bag" method.
Basically, you wet the window with an ammonia/water solution, put a (pre-cut to size) piece of black trash bag on the window and smooth it so there's no wrinkles or air bubbles, let it sit in the sun for a while, and peel it off.YouTube search

Thanks for all the great tips.

"Goo-Gone" will soften the glue. Take a razor blade and score the tint paper and let the goo gone work. Comes in a spray bottle or dripper type bottle. I've removed all things Gluey with it and it lubricates as good as windex.