Slow Radiator Leak - 2007 Pontiac G6

I drive a 2007 Pontiac G6 with the 3.5L V6 engine with approximately 50k miles. Over the last 2 years, I’ve been experiencing a slow radiator leak that neither the dealer, or my trusted mechanic have been able to identify. Every 3 - 6 months, I notice that the radiator fluid levels are low in the reservoir tank, which I’ve simply been re-filling. The system is holding pressure without a problem, and I am not finding any fluid on the ground, or anywhere in the engine, I do not see any smoke coming out of the exhaust system, and my mechanic did not note any coolant in my oil during my last oil change.

I’m hesitant to use a product like Bar’s radiator stop leak, but am open to trying it if others recommend.

Any suggestions on how to diagnose, or fix this slow leak … wherever it may be coming from … would be much appreciated!

Do not use stop leak. If car is under warranty, or was when it started leaking, then insist that the dealer fix it under warranty. Where there is a will there is a way to find the leak.

You are calling this a radiator leak but keep in mind it that it could be in many different locations, a hose or in the engine, there are dozens of possible locations. The last thing you want to do is add some kind of leak stopper. Having the overflow tank get low every 3-6 months is an extremely tiny leak and will likely never exhibit any symptoms unless the leak becomes larger. One thing that could be done is adding some UV dye to the coolant, drive the car normally for a few weeks and then go over the engine compartment with a UV light, it might show up.

I think I’d just change the radiator cap, check all the hose connections and so on, and just wait until it gets worse. I wouldn’t use stop leak although every new car has stop leak in it. I’d pay particular attention to the bottom pan below the radiator. If there is a slight leak along the plastic tanks, it can be following the seam and drip a little on the bottom. You could also have a little crack in the plastic overflow tank.

As mentioned, no stop leak. Have you checked the overflow reservoir and the tubing to it for cracks or leak?