VVC burning slightly amount of oil at very high revs

Hi, I have a MGF VVC with almost 100k Miles and only at very high revs (over 5 or 6000 rpm) you can smell some burnt oil. I never have to fill up the oil though, so it does not seem to be a big problem (I drive about 2 to 4k Miles per year, it is a hobby car and at the end of the summer no change in oil level can be noticed, so it can't be burning a lot).

MOT emissions look good, but I have some questions anyway:



Can this do harm to the catalytic converter on long term?

What can cause this (I understand that valve seals or valve guides should also leak oil at lower revs and especially at start up, I am not seeing this).

Candidates I see are: leaking piston ring(s) or pressurising of the engine under high revs?



Any comments welcome, especially if you ahem any good ideas to a good method to check what can cause this.



One of the cylinders showed some oil when I took off the exhaust header, so I tend to think about a leaky piston ring (but hope it is a valve seal :-))

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