I've owned it for 12k miles and I've probably done 3 or 4 oil changes, 2 with synthetic oil. I think an seafoam oil treatment might be in order. I think your right about it being varnish, but there is definitely corrosion on the inside of the valve cover.
The sparkplugs had a good seal, really struggled to pull them out the first time, now they come out easily. I think the coils were replaced at some point, they aren't numbered annoyingly and they don't have a date on them like the stock ones do.
For some reason my denso spark plugs had this neoprene ring around them, IDK if its from the after market coils, but this neoprene stuff was falling apart and its resting on the lip where the spark plug usually sits. I'm worried I might get shreds of this neoprene substance in my cylinder. Should I worry?
Oh and I counted the teeth on the timing chain tensioner. I think there was 10 or about that. Anyone know how many teeth there are total?
Answered my question: there are approximately 20 teeth on the tensioner total. So I'm at half life. Had to pause and count teeth on
this video.