My friend (mechanic) keeps trying to convince me this is a brake line leak

So my friend was helping me with my truck, and he noticed fluid stains on the Front Right frame by the brake line.



Looking at the brake line, it looks like it is a little scuffed, I can't tell if its just the rubber coating that is rubbed up or if the line is busted up.



I put a piece of paper towel down to see if it was leaking while driving and so far it looks completely clean in the area that the line is. There is a small yellow spot indicated in the spot where the arrow is, but I believe it is from my heating core, as it is right above the leak spot (which is leaking as I smell antifreeze inside).



We tried pumping the brakes, which didn't cause anything to come out of the line. The brake fluid level is normal, and the brake feel fine to me. I think it is just fluid from my heating core all over the frame, but he is convinced its the brake line. We saw yellowish drops of fluid when the leak was wetter.

it could be brake fluid, but I doubt it's a leak if you pumped the brake and the pedal feels fine and you can't see any leakage. It might just be spillage, or it might be from bleeding the brakes, or even previous other brake service. Try to smell the fluid. if you can, coolant smells sweet. Are you sure it's not just condensation from the a/c?

If you smell antifreeze. More than likely you're right and it is the heater core this is leaking.