The mechanic from the workshop gave it to me for testing. I had used another sealant for block crack sealing 6 months ago, which worked partially. With this one, which is much cheaper, the leak stopped. It is relatively thick and needs good shaking before use. The process I followed: With a cold engine. I removed about 1 liter from the lower cap of the radiator. I dissolved 150cc of the sealant in the liter I removed. I started the engine and turned the cabin heating all the way up. After 2 minutes, I began to very slowly add the solution to the radiator. When it was full, I put the cap back on. I let it idle for 1 hour. The total coolant in my engine is about 4 liters. The 375ml package is for up to 10 liters of circuit. After application, we regularly check the level in the expansion tank. If I don't change the comment, it means everything is going well.

From the result, I found it useful. A cleaning of the cooling system was done beforehand. I don't see any leaks. How much money have we all paid to "professionals in the field" for water pumps, thermostats, and other spare parts without them telling us how to properly maintain the cooling circuit....