I wouldn't put any make of stop leak in the cooling system. You'll just plug up the radiator and heater core and make hundreds of dollars worth of repair bills. Where's the leak? If it's the water pump you need to replace it. You're going to end up fixing the leak or ruining the head gasket by overheating the motor. Have the cooling system pressure tested if you don't know where the leak is.

What type of radiator does your car have? If it has the aluminum radiator then be sure and use ONLY stop leak made specifically for aluminum radiators. You could always drop four of five whole peppercorns in there for a cheaper and positively compatible fix!

Neither! Put that sh*t in the trash, it'll plug the small coolant ports running through the head(s), it'll plug the heater core, the small ports in the radiator. Do yourself a huge favor, just fix what's broken and don't put that garbage in your engine, or you'll have more serious problems later

If your radiator doesn't have a cap, then just add it to the surge tank.

Biggest problem with stop leak is that most people use too much and THAT can plug up the heater core. Use EXACTLY what the bottle says and it MUST go into the radiator, not the overflow bottle.

If you're set on using this stuff, put it into the radiator.

Don't do it. It's not worth it and it won't solve the problem.

The heater core has smaller cooling tubes than the radiator. Bars leak CAN plug the heater core. Why would you want to do that?

If you wont go to the technician or the parts people to get this figured out. use BLACK PEPPER.

It floats, is non clogging, lasts forever in there, and when it finds a way out, it plugs the opening little by little.

But you do not say your make, model, year, or current diagnosis, we are left to guess there is a leak.

You could have gasket, thermostat, cooling fan, head or block trouble, so I recommend seek professional help.

If you know you already cooked it, then it is cooked, you cant change it back without specific careful diagnosis and repair.

Stopleak is supposed to be used by a tech after diag and evaluation, the customers special circumstances require it, and then there are seven or eight ways to look at it.

Every one of those repair orders would say, no guarantee, customer declined repairs, and not responsible for continued overheating.

Now, the pepper, it's ingenius, try it.

Update your question and candidly tell us what you are trying to fix.

The surge tank is not the radiator. It says radiator put it in the radiator. Why you would use the stuff is beyond me anyway. Cure in a can seldom work.