Question
I live in sacramento CA and I have a silver maple that seems to be in a little trouble. I've had 2 tree companies come out and each gave different reasons. The trunk is showing tears or gashes, not too deep but there are about 6 of them. We also have a dark leaking substance coming from various spots. The tree is getting pretty decent water and the leaves are plentiful. One guy said it was caused by a beetle and the other called the ooze tar and said it was a disease.

Answer
Hi Andy,

If there were a problem with beetles, you should see holes in the trunk.  Often, in association with the holes you will find sawdust.  Should you find this type of sign on the tree, I can help you with a treatment.

More likely, if you are seeing cracks and oozing, it sounds like a canker problem.  The most common type of canker problem that causes oozing is a Phytophthora canker.  Unfortunately, there is no cure other than taking good care of the tree.  Over time, it is likely that the canker will girdle the trunk and cause death of the above ground portion.  So, you will want to closely monitor the tree and have it removed before it becomes hazardous.  

There are both native Phytophthora cankers and exotic.  In most cases, the problem is due to a native Phytophthora problem. You can learn more about these diseases at the following websites.
http://agri.nv.gov/PLANT_PATHOLOGY/2006/BleedingCankerDiseaseSilverMaples.pdf
http://extension.umass.edu/landscape/fact-sheets/phytophthora-bleeding-canker

In some areas of California, there is another disease caused by a Phytophthora species which has been more recently introduced.  The pathogen is P. ramorum and causes Ramorum blight and is also known as sudden oak death.  There is much on the internet about this disease, but I do not believe it is found in the Sacramento area.  If you are concerned, you should contact your local county extension office. You can find their contact info/location on this website:
http://ucanr.edu/County_Offices/

Good luck with your tree!
--Jen