JLM Lubricants

JLM Engine Oil Stop Leak


 / 250ml

  • Stop and seal motor oil leaks
  • Reduce emission blue exhaust smoke
  • Reduces oil consumption
  • For all Petrol, Diesel, Hybrid, LPG & NGV cars
  • Can be mixed with all engine oils

Worn engine oil seals create leaks that are messy, bad for the environment and your wallet. While replacement seals tend to be inexpensive, accessing them tends to involve significant dismantling and high garage labour bills. JLM’s Engine Oil Stop Leak additive provides an inexpensive solution.

Product information

As they age, oil seals lose their flexibility, which affects their sealing properties. This process worsens on engines that have suffered from neglected oil changes, or endured low-quality (or incorrect specification) lubricant that contained insufficient oil seal preservative additives. JLM’s Engine Oil Stop Leak contains the latest in seal-swell additive technology that helps restore their pliability, which also compensates for a degree of wear on the seal lip surface.

JLM Lubricants’ Engine Oil Stop Leak also supports the lubrication system of an older engine, by enhancing oil viscosity slightly. Additional benefits include the potential to improve both oil pressure and cylinder compressions, along with the possibility to reduce the quantity of lubricant burnt within the combustion chambers, thus reducing oil consumption further. For cars that suffer from excessive oil consumption but exhibit no external leaks, JLM’s Stop Smoke offers a more targeted solution.

For these reasons, JLM’s Engine Oil Stop Leak is beneficial for older, higher mileage engines. It does not offer a solution for oil seals that have collapsed, or have suffered from mechanical damage, such as a puncture.


Engine Oil Stop Leak fits JLM Lubricants’ company policy of offering cost-effective but advanced chemical solutions that are straightforward to use.

While it can be added to the oil at any point, JLM recommends dosing at service time. An oil-flush additive should be added to the sump, for which JLM Lubricants recommends its JLM Engine Oil Stop Leak before the old oil is drained and the fresh lubricant added.

Substitute 250ml of the new oil with JLM Lubricants’ Engine Oil Stop Leak. 250ml JLM Engine Oil Stop Leak treats 3 to 6 litre of motor oil. Never overfill the sump, which risks causing additional problems, such as pressurising the crankcase that risks increasing oil leaks.

As its seal-swell ingredients are so effective, it should not be used in other hydraulic systems, such as automatic gearboxes, Dual Clutch Transmissions (DCT), or power steering systems. It swells all rubber components within those systems indiscriminately, affecting the intended operation and may even enhance wear. JLM’s Engine Oil Stop Leak is strictly for the lubrication systems of combustion engines, only.

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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 from a potential distributor.

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 extreme 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 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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