Just went for a 10 mile drive getting the oil up to 203 degrees. Still no sign of leakage.
Further thoughts on the cap....if your coolant cap requires pliers to remove, you can bet it was overtightend past the stop lug. The blue graphic on the cap should be oriented left to right observed from directly behind the car. If it's oriented front to rear it's been turned past the stop lug in an overtightend state. The little lug that functions as a click stop indicating the fully tightened position is pretty small and a soft nylon type of plastic versus the harder plastic of the fill neck. It would be easy to go past the stop point deforming the lug and it would lock in place past the designed ramped recess in the filler neck. Then the next time it's loosened it will require greater force to open further damaging or breaking off the stop lug on the cap.
The new updated version has a much more substantial stop lug that would have to be forcibly turned past the stop point. Breaking the stop lug on the newer version should be quite difficult to do.
So, if you have had to use pliers to remove your coolant cap, you need to inspect the cap and the filler neck. You likely may need to replace one or both.
I would imagine that newer manufactured Caymans will have the updated design. My car was purchased in early March 2018 and built in December 2017.
2018 718 Cayman GTS
Last edited by wriggly; 04-11-2019 at 06:58 PM.