Review on Bar's Leaks HG-1-4PK: Head Seal Blown Head Gasket Repair 🔧 - 33.8 oz (4 Pack) - Ultimate Fix for Head Gasket Issues! by Duane Barker

My heater core and radiators are definitely clogged. I had previously tried their other headgasket sealant without success so I drained, rinsed and added this. Now I have no heat but honestly I think my heater core used to be partially blocked as I only got warm at low fan speeds. Now I have no heat at all. Worse still, my engine temperature is 10 degrees warmer than before treatment and increases noticeably when it warms up and I'm stuck in traffic. I think my radiator is now significantly clogged. Only the top feels warm while the rest feels cool. The bottom line is that this might work for you, but I wouldn't recommend it if you've tried sealant on a head gasket before. It may have sealed my head gasket since the bubbles in my reservoir have stopped. The truck will sit for 4 days before I use it again and that will be the deciding factor. It always misfired after several days of inactivity. Then I update. Update: No check engine light or white smoke. I changed the cooler. I think I made a mistake putting this substance directly into the upper radiator hose. I did this because when I poured oil into the radiator, it didn't run into the radiator. This material is really thick. It just sat on the underside of the old radiator even after about 50 miles of driving. If I had to do it all over again, I would drain a gallon from the system, then mix that substance with that gallon and pour in half diluted. I'll try flushing the heater core.