We researched your site and found that there is no treatment except to drill a hole 12 to 14 inches below where the trunk is oozing. How many holes should we drill? Should we pump air through the holes to dry it out? Oxygen should kill anaerobic bacteria. We have three trees affected and they are very mature and we hear they usually do not live that long but these trees have been there for at least 30 years. Many thanks.
How to Treat Bacterial Wetwood in Douglas Maples?
First, are you sure that slime flux, or bacterial wetwood, is the cause of the problem you are having? There are a number of conditions that will result in oozing: https://www.gardeningknowhow.com/ornamental/trees/tgen/what-is-tree-sap.htm
If it is slime flux, most tree experts agree that there really is no treatment, except making sure the tree has sufficient water, and correct nutrition. Drilling holes is not a very popular approach, for fear of actually spreading the disease. If the area is not too large, clean cutting the wound may be useful. These articles have more info: https://extension.colostate.edu/pubs/garden/02910.html
If you don't have a professional diagnosis, this could be the time to consult a certified arborist, nursery professional, or the nearest botanical garden.