Originally Posted by naftali

Another old issue and very bothering: Even when the muffler original YS O ring slides nicely on the header at the start of the flight, after 8 minutes or so, the O ring is stuck to the header, as if it is glued to it. I tried freeing the O ring every flight, lubricating with vaseline, anti seize, polishing the header - all to no avail.
After about 8 flights the O ring starts creeping out as can be seen, loosing seal and leaking exhaust gas.
The engine performs nicely otherwise, oil is 10% Morgan Low Smoke.
Any cure?