Very astute observation Ray.

Oil? Combatkid's castor at 25% b/v. More than required, but the engine is young, and I still do not fully trust it. That said, it does run well.

I noticed the blackish ooze. It did that on the first fast run during the first session as well.

I think the light colour of the bench laminate makes it look worse than it is. It is more dark blue/green (dye in the KCB kero?).

If you look at the side of the fuel tank the true colour of the exhaust oil is more akin to "dark honey".

It did seem to clean up in the run after the one I video'd and posted.