If it's seeping a little and just staining, then you can leave it for now but make sure you get it fixed soon. If its dripping, then it's on the edge of failure, you should replace it asap to prevent damage.
PS, I'm not sure about stop leak chemistry, but I doubt that it's compatble. Plus, I hate stop leak since they form little balls. In addition, on a turbo engine, a ball of stop leak getting stuck in your turbo = turbo death. Don't use it. Also, if your coolant is pink, then don't add green, blue, or orange coolant, stick with VW .
I had a 944 porsche with a leaky radiator, used stop leak and not only did it not stop the leak, but it caused gummy gel balls to show up...and that was used with green coolant. What a lousy product, I would avoid using it with any turbo car after seeing what it did to my car.
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