Radiator & Engine Block Stop Leak (REBSL)

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Radiator & Engine Block Stop Leak (REBSL) - REBSL-500

Radiator & Engine Block Stop Leak (REBSL)

Nulon Radiator & Engine Block Stop Leak  with DuPont™ Kevlar® fibre & liquid resin provides the ultimate strong long lasting fix. Formulated to permanently seal radiator leaks, inlet manifolds and engine block leaks, cracks, leaking welch plugs and leaking gaskets without costly mechanical repair. This unique microfibre technology seeks out and plugs small leaks and cracks that cause coolant loss, loss of pressure and overheating. 

The DuPont™ Kevlar® fibres mesh and plug the leak or crack which are then encased in a hardened liquid glass resin for the ultimate permanent water tight seal.

Nulon Radiator & Engine Block Stop Leak can be safely used in cars, trucks, vans, utes, and light commercial vehicles. Safe for all plastic, aluminium and metal (copper / steel) radiators, heater cores, gaskets and welch plugs. Safe to use with all types and colour of glycol anti-freeze/anti-boil and water based coolants.


  • Seals radiator and inlet manifold leaks and cracks, welch plugs and leaking gaskets and pipe leaks fast
  • Contains DuPont™ Kevlar® fibre and liquid glass resin for the ultimate permanent water tight seal
  • Stops leaks from small pinholes (up to 0.8mm diameter) and small cracks (up to 0.8mm width) in any cooling system
  • Saves costly mechanical repairs
  • Maintains cooling system pressure and temperature to prevent overheating
  • Safe to use with all types of glycol anti-freeze/anti-boil coolants and water based corrosion inhibitors

How to use

This product is designed to be added to the coolant – DO NOT ADD TO ENGINE OIL.
If your coolant is dirty flush the coolant and replace with the correct recommended coolant, before adding this product.

DANGER: Ensure the radiator is cool before opening the radiator cap to prevent scalding.

Make sure when adding Radiator & Engine Block Stop Leak, radiator fluid is above internal radiator core.

  • Shake bottle contents and pour Radiator & Engine Block Stop made with DuPont™ Kevlar® fibre directly into the radiator. If using in a small capacity radiator (4 cyl) use half a bottle to prevent overflow.
  • Fill radiator and overflow tank to correct level and replace radiator cap.
  • Start the engine and turn the heater to hot and fans to high to circulate coolant.
  • Leave vehicle to idle for 15 minutes.
  • Turn engine off and allow engine to cool.
  • Check coolant level and top-up if needed. Drive the vehicle as normal.


  • 4 cylinder engines smaller than 5 litres radiator capacity use half a bottle.
  • 6 and 8 cylinder engines up to 15 litres radiator capacity use one bottle.
  • For larger cooling systems use half bottle per 7.5 litres of radiator capacity.

First Aid

For advice, contact a Poisons Information Centre (Phone e.g. Australia 131 126; New Zealand 0800 764 766) or a doctor (at once).

Pack Sizes


500 ml
6 Per Carton
Barcode: 9311090 004559