So you pulled an old car out of a shed somewhere and got the engine freed up and running. But it's got a small coolant leak and you're not in a position to tear into it too deeply quite yet. And you're skeptical of the $40 to $60 a bottle Miracle Liquid Head Gasket Repair stuff. Well I was in a similar situation recently with an off-topic used truck I'd bought. It had a visible leak at the back of the cylinder head that I assume was the head gasket. If it got hot enough it would vent steam from the back of the hood, steam cleaned the firewall and would leave a puddle on the ground under the transmission and engine area. It got to be a regular routine adding coolant to it for a couple of months. But at work we sell a GM Cooling System Sealant that was originally recommended for use in the Northstar engines that tended to be kind of weepy even after replacing the head gaskets. They're like big horse-pill looking things and a pack of 5 of them should be around $5 or less at most GM dealers. So when topping up my coolant at work I added 3 of them to the radiator. After a few days I needed to top things up again. After maybe another week or so I added more water again along with the remaining 2 tablets. But then, after maybe another 4 or 5 days, I discovered that it didn't need any topping off. The level in the reservoir and the radiator were still right where I'd last filled them. I've been checking it regularly since but still haven't had to add any coolant for at least the last month. In other words, this stuff seems to be working. But the strangest thing is the main ingredients in these sealant tabs. Stuff like powdered ginger root, ground almond shells and turmeric. I can't guarantee it will work for you but it's cheap enough to try. And with a little patience you might be pleasantly surprised. GM Cooling System Seal Tabs #12378255 $4.16 at most GM dealers.