Just wondering if anyone has any experience using the Prestone Stop Leak products (http://www.prestone.com/products/coolingSystemTreatments.php) to fix a leak in the heater core or seals.

I get a wiff of maple syrup smell every so often so I am beginning to think that I am starting a small leak. Haven't seen any liquid on the floor or fogging of the window.

Is there any risk in using these products? I just figured that if I eventually have to replace the seals or the heater core, it can't hurt to try the cheap and easy solution first.