JLM Lubricants

JLM Radiator Stop Leak


 / 250ml

  • Stops leaks in radiators & waterpumps
  • Compatible with all types of coolant & antifreeze
  • Protects against oxidation and blockages
  • Easy to use pour & go formula
JLM Radiator Stop Leak J04811 JLM LUBRICANTS

JLM Radiator Stop Leak seals holes up to 0.9 millimetres in radiators, coolant hoses, coolant reservoirs, heating radiators, cylinder heads, head gaskets and water pumps and cleans and prevents oxidation.

Product information

As soon as Radiator Stop Leak is added to the vehicle’s cooling system, its active components seal any leaks that exist up to a diameter of almost one millimetre. The cleaning effect of JLM Radiator Stop Leak makes is ideally suited to preventing problems in the cooling system.

JLM Radiator Stop Leak is suitable for all common cooling systems, water pumps and heating systems in all vehicles. Radiator Stop Leak has an anti-corrosive effect making it suitable for use as a preventative or for maintenance JLM Radiator Stop Leak can be mixed with all types of after-market coolants and antifreeze.

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JLM Lubricants

Great addition

"This is a great addition to the products in my workshop. We continuously see fantastic results in the recovery of emissions and engine performance, among other things."

- Paul Finn

JLM Lubricants


"I was very skeptical, but after using the product and starting my car, I couldn't believe my eyes ... the yellow light in my car was no longer on!"

- Kevin Kalo

JLM Fixing cars

Surprising­ly good

"I never thought that JLM would surprise me so much. It gets better and better every time. I will continue to use these products. The fantastic results speak for themselves. Keep up the great work."

- Andrew Watts


These are the most common questions we get.

Do any of the JLM additives help the performance of the high pressure diesel fuel pump?

J02330 Rapid is perfect for pump and injectors!

Is it OK to use the JLM Extreme Clean and the DPF Cleaner together?

No, this will not have a positive effect. In fact it may cause an adverse effect. And also the risk of overdosing! Never combine fuel additives


Will JLM Bluboost dissolve existing crystal infestation or is it more like a preventative product?

JLM’s Bluboost additive cleans and prevents crystal formation in the AdBlue® dosing system. It also conditions the AdBlue® fluid for a longer time to ensure proper working of the AdBlue® and SCR system. This helps prevent performance loss and the often-subsequent expensive repairs. It also reduces foaming at low temperatures

Is the JLM Engine Oil Flush safe for use with wet belt engines?

Our JLM OIL FLUSH is safe to use with ‘wet belts’ (TBIO). This is mainly because we use non solvent and premium pack of oil cleaning additives.


Does the Petrol Emissions Reduction Treatment also clean the catalytic convertor?

The catalytic converter is not a filter, it functions by converting harmful emission gases into less harmful gases. The filter can become contaminated if for example there has been an oil leak, and when this happens the filter needs to be replaced. There is no additive or chemical that will remove physical contamination from a catalytic.

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