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How to use RISLONE radiator stop leak

hi i have a small crack in my radiator (on the top) so i purchased Rislone radiator Stop leak. i realized that im supposed to pre-desolve the pellets, but im not exactly sure how. do i put he whole container (un-opened) under running hot water. or am i suppsed to put the liquide and pellets directly in warm/hot water?

I would recommend that you get a new radiator (or have yours repaired, if possible) rather than introducing a substance that is designed to fill small cracks into the small passages of your engine block. Those stopleak products are fine if it’s an old crapbox that you don’t want to put any money into to fixing, but you should be ready to ditch the car if things go wrong.

I’m with shadowfax. Find a good independent shop. Having a new radiator put in might not be that much.

Take a tablespoon of ground black pepper and pour it in the radiator and fill the radiator. Drive the vehicle back to the parts store to return the stop-leak product. By the time you get there your radiator leak will have stopped.


You’d be surprised how cheap a new radiator (part, not labor) is. Go to and see. If the ‘crack’ is in a plastic tank, it’ll just get worse. Better to replace it now, rather than risk a major leak and overheating the engine, which could ruin it.

What make/model/year/miles?

the pettets will seal any small hole like the passages in your heater core a new rad. ranges from 85.00 up to 200.00 + but what kind of car?