Question
QUESTION: i  have a 35yr old locust tree and it's been leaking sap all summer and all over my car.  is this normal and will this damage the paint and clear coat on my cars.
thanks

ANSWER: Check and see if the sap is sticky and seems to fall is small mist like droplets. I would think that the trees have sucking insects (scale or aphids). These insects suck the plant juices fro the plant and secrete a substance called honeydew which is high in sugar content and sticky. A sooty mold will grow on this honeydew and give the black appearance. I would guess these are scale insects. These tree can be treated with an insecticide called Bayer Advanced Tree and Shrub Insect control to kill the sucking insects. This product is applied to the soil around the tree and the roots will carry the insecticide to the leaves and twigs and when the insects suck the plant juices they are killed. This treatment will last the full season and prevent further insect infestations. The sooty mold will go away after the sugar source is stopped. Check with your local garden type store for this product. No it is not good for the car but with washing it should not damage the paint.
Here is a web link to the Bayer product.

http://www.bayeradvanced.com/tree-shrub-care/products/12-month-tree-shrub-insect.


---------- FOLLOW-UP ----------

QUESTION: The problem is I'm not able to  wash the cars every 15min sinc its constantly dripping and it's a corporation tree so it'll take time to explain this and have them take care of the issue .  I'm just fearful of my paint on my cars.  
Thx

Answer
I would wash the car weekly and try to find a parking place as far from the tree as possible. At least until the trees are treated or drop their foliage. Here are a couple of web link on how to remove the sap from cars.

http://howto.yellow.co.nz/automotive-and-marine/vehicle-maintenance-and-repairs/

http://www.usautoparts.net/bmw/repairs/detailing/tree_sap.htm