Look for a stop leak that corresponds to your knowledge and competence. I prefer one step radiator leak stop solution for quick fix. Some sealants require that the entire system be flushed before applying the sealer. It could be beyond your ability level or inconvenient due to the car's position. Look for one that doesn't require flushing if you're trapped on the side of the road or have minimal experience working on your automobile. For mending large leaks, specific formulations are more effective than others. You'll need a formula that can seal the hole in your cooling system no matter how big it is. Most coolants can efficiently plug a leak up to.250mm in diameter. It's crucial to think about how often you'll need to use it and how it'll affect your vehicle in the long run. You can reuse remember that fluid several times before it runs out. The more leaks you have in your radiator, the more difficult it will be to stop them all.