Has anybody had this issue? I'm pretty sure this is not from getting too hot nor too full. I think its from slosh in the tank. The cap has a small spongy "gasket" in it that appears to be soaked with coolant. I've cleaned the tank off quite a few times and noted that the coolant traces appear later. I'm thinking it needs a new cap without the spongy gasket.

coolant 1

coolant 2

coolant 3

11-year-old foam gasket that lives in hundreds of degrees of heat. Probably a bit loose now. I'd say get a new one.

Or upside down.

Ya I think I could use a new cap too after all these years on The PA. The tie down ring was missing a long time ago & mine weeps out a bit too.

I guess I'm lucky, mine'* the old-fashioned screw-on kind with the vent on top.