Is there oil on your transmission?? Is your car over 10 years old?? Need a new clutch? Well while the transmission is removed to replace your clutch and/or flyhwheel this little part is a cheap insurance policy against oil leaks in the future.
This is the rear main seal that seals the oil from leaking between the crank and the oil pan. It is extremely easy to replace while the transmission is out for downpipes, clutch, and/or flywheels.