WYNNS Engine Stop Leak (Ref. W50672 – 325 mL) delivers a precision-formulated treatment that revives and seals aging rubber and neoprene engine seals. Designed to prevent and halt oil leaks caused by dried or shrunken seals and O-rings—without requiring dismantling. Compatible with petrol, LPG, diesel, and hybrid engines, this additive works in both mineral and synthetic lubricants. One bottle effectively treats up to 6 L of engine oil. For best results, add at every oil change and drive as normal; full effectiveness arrives after roughly 300 km of use. The formula won’t alter your oil’s viscosity or engine’s performance, and it's completely safe for catalytic converters and modern sensor systems.