I've noticed on a mature Grevillea (Misty Pink, I think) a spot where all this amber sap? is coming out. Since I took these photos, it has gotten bigger.
Anyone have any idea what it is?
I'm no expert on this, though I've had the same problem. Checking my references, seems it could be caused by borers or minute insects that attack the bark and or sapwood, causing the tree to 'bleed' in defence of the problem. I'd clean away the 'bleeds' and check for holes or other damage to the bark and treat the area with methylated spirits. Metho won't hurt the tree but will kill any pests that are causing the problem.
if I find any borer holes, should I try to spray the metho into the holes?
Yes annie, you can also poke a wire into the hole(s) as far as it will go, which should also kill the pest. Let's know how you get on.