Liqui Moly Oil Leak Stop engine oil additive — 300 ml, restores rubber seals & reduces oil leaks

Liqui Moly LM 1005 Oil Leak Stop is a 300 ml additive designed to restore hardened rubber and plastic engine seals to reduce oil leaks, lower oil consumption and quiet noisy engines.

LM 1005 is formulated to swell and rejuvenate seal materials such as shaft seals and valve stem seals without disassembling the engine. By improving seal pliability it helps stop or slow oil seepage, prevents fresh oil from dripping under the vehicle, and reduces oil dilution. The additive also assists piston rings and valve guides to restore better combustion sealing and reduce engine noise.

How does LM 1005 stop or reduce oil leaks?

The additive works by penetrating and softening oxidized or shrunken rubber and certain plastics used in engine seals. Restored seal geometry reduces gaps where oil can escape, which lowers visible seepage and puddling underneath a parked vehicle.

• Softens hardened seal compounds to restore flexibility and sealing contact
• Expands slightly shrunken seals to close micro-gaps
• Compatible with common automotive rubber and plastic engine seals

Will it lower oil consumption and engine noise?

By improving the sealing action of piston rings and valve stem seals, LM 1005 can reduce the amount of oil entering the combustion chamber and burning off. Better sealing also reduces blow-by and the mechanical noise associated with worn valve guides and rings.

• Helps piston rings seat more tightly to reduce oil passing into combustion
• Improves valve stem seal performance to cut oil seepage past valves
• May reduce rattling and ticking caused by loose sealing components

How do you use Liqui Moly Oil Leak Stop safely and effectively?

Use the product according to the vehicle manufacturer’s directions and Liqui Moly dosage guidance. Typically the additive is poured into the engine oil at operating temperature; avoid overfilling and follow recommended refill volumes.

• Add to warm engine oil for better product mixing and penetration
• Follow the 300 ml bottle dosing instructions relative to your oil capacity
• Check seals and oil level after treatment and top up if needed

How long does it take to see results and are there limits?

Some improvement can appear after a short driving period, but full effect may require several hundred kilometers of normal operation to allow the additive to circulate and condition all seals. It is most effective on seals that have become brittle or slightly shrunken; it cannot repair mechanically damaged or severely ruptured seals.

• Initial effects often seen after short-term driving; full conditioning may take longer
• Best suited for gradual seepage and softening-related leaks, not large tears
• Not a permanent fix for heavily damaged or externally cut seals

Who is this product for? Liqui Moly LM 1005 Oil Leak Stop is aimed at vehicle owners, maintenance technicians and fleet managers who want a non-invasive, in-engine option to reduce oil leaks, lower oil consumption and quiet seal-related engine noise. It’s suited to passenger cars, light commercial vehicles and older engines showing seepage from shaft seals, valve stems or increased oil usage due to degraded sealing components. For severe leaks or structural seal failure, mechanical repair or seal replacement remains the correct solution.