Now these VW engines are getting on for 50 to 60 years old its not uncommon to fit a new flywheel oil seal and it still leaks, This is because the flywheel snout is scoured due to age. Fitting the double lip seal means that it seals in 2 places on the flywheel limiting the chance of leaking. Top tip : Make sure you lubricate the flywheel snout before installing it back onto the engine, Failure to do so will cause the new seal to fail on start up as the metal will damage the sealing lip. Lubricate the snout with rubber grease, silicone grease, or if you don't have those to hand use engine oil. fits 1961 onwards 1200- 1300- 1500 and 1600cc engines Does NOT fit 1700-1800 or 2000cc engines.