Charles
Mine just has an o ring. Its an early car but it seems to work fine.
What was fitted to yours originaly
I originally had a different oil tank probably like yours. It was upgraded to the 2014/13 tank with the nut for talking out the oil.
these newer tanks have the metal lines to show oil depth rather than using a dipstick. Hence the cap is different.
The newer ones have some kind of rubber sheet gasket. But it deteriorated. Hence I am trying out gasket seals.
its actually quite tricky choosing the correct material because of the high operating temp and the sharpness of what it fits on. If it disintegrates on a long journey and blocks the feed pipe it wont be good so I want to find whats best.
a tough matrial that can form a good seal with perfect oil and high operating temp resistance.
