I smelled oil burning and saw small puff of smoke from right side of engine. So I ordered new gaskets for valve covers.

Took everything off and found RH outside gasket leaking oil. Also found LH spark plug seals had leaked terribly and saw oil halfway up tube. Lucky the car did not misfire. The seals were hard as rock

One month short of 3 years since I last replaced them. I retired in 2014 so the car does not get much mileage now. Must just be age related.

I found a great deal on victor reinz set from rock auto. I had used Jaguar original parts last two times but not anymore.