Tree gunk on windscreen

CurlySue2017

Silverpete said:

Try WD40 - it dissolves most resins

This works and I am talking from recent experience.
My car roof was full of it and jet washing / standard car wash just did not shift it at all - it looked black, almost like tar stains or something but it was definitely tree sap.
In the end the only thing that worked was WD40 and A LOT of elbow grease!! 
We (hubby and myself) had to spray very small sections with WD40 and then with a cloth over the end of our fingers, rub hard in small sections......all over the roof of the car.  Cleaning like we normally would just did not work, we had to really concentrate on very small areas at a time and rub, rub, rub........  

freemurphy

Use a cotton pad dipped in surgical spirit to dab at stains. The alcohol should evaporate and not leave any marks. 

Savvy_Sue

You missed my thread asking about a car cover: https://forums.moneysavingexpert.com/discussion/6605943/suitable-car-cover-with-radio-aerial-at-rear-of-roof/p1

There was universal advice NOT to bother. I can confirm that now it has rained the problem has improved no end! And I found that HOT water was quite effective on the windscreen - didn't worry about the roof because it was only going to get mucky again. 

We used to get it hand-cleaned fairly regularly, and that definitely gave good results, but it didn't last. And now the place we used to use has closed and we haven't yet found a convenient alternative. 

I'd go back to using a sheet if I found it necessary.