I did not run it in a test-bench at all, as I read somewhere (in the manual?) that the engine must not be run with a propeller. Though if you recommend this, I will try it.

I do not know the brand of the exhaust (probably a no-name). It's a short one with the outlet in the bottom, facing upwards in an angle, which might prevent the oil from exiting it.

Is 18% oil and 5% nitro still enough, or should I buy some other fuel?

Thanks for helping me.